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Encyclopedia > Chemical element
The periodic table of the chemical elements
The periodic table of the chemical elements

A chemical element is a type of atom that is distinguished by its atomic number; that is, by the number of protons in its nucleus. The term is also used to refer to a pure chemical substance composed of atoms with the same number of protons.[1] Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... The Periodic Table redirects here. ... See also: List of elements by atomic number In chemistry and physics, the atomic number (also known as the proton number) is the number of protons found in the nucleus of an atom. ... For other uses, see Proton (disambiguation). ... The nucleus of an atom is the very small dense region, of positive charge, in its centre consisting of nucleons (protons and neutrons). ... Water and steam are two different forms of the same chemical substance A chemical substance is a material with a definite chemical composition. ...


Common examples of elements are hydrogen, carbon, nitrogen, and oxygen. In total, 117 elements have been observed as of 2007, of which 94 occur naturally on Earth. Elements with atomic numbers 83 or higher (bismuth and above) are inherently unstable, and undergo radioactive decay. Of the first 82 elements, 80 have stable isotopes. Elements 43 and 61 (technetium and promethium) have no stable isotopes, and decay. The elements from 83 to atomic number 94 that have no stable nuclei, are nevertheless found in nature, either surviving as remnants of the primordial stellar nucleosynthesis which produced the elements in the solar system, or else as produced newly as short-lived daughter-isotopes in the natural decay of uranium and thorium.[2] This article is about the chemistry of hydrogen. ... For other uses, see Carbon (disambiguation). ... General Name, symbol, number nitrogen, N, 7 Chemical series nonmetals Group, period, block 15, 2, p Appearance colorless gas Standard atomic weight 14. ... This article is about the chemical element and its most stable form, or dioxygen. ... General Name, Symbol, Number bismuth, Bi, 83 Chemical series poor metals Group, Period, Block 15, 6, p Appearance lustrous pink Standard atomic weight 208. ... Radioactive decay is the process in which an unstable atomic nucleus loses energy by emitting radiation in the form of particles or electromagnetic waves. ... For other uses, see Isotope (disambiguation). ... General Name, Symbol, Number technetium, Tc, 43 Chemical series transition metals Group, Period, Block 7, 5, d Appearance silvery gray metal Standard atomic weight [98](0) g·mol−1 Electron configuration [Kr] 4d5 5s2 Electrons per shell 2, 8, 18, 13, 2 Physical properties Phase solid Density (near r. ... General Name, Symbol, Number promethium, Pm, 61 Chemical series lanthanides Group, Period, Block n/a, 6, f Appearance metallic Atomic mass [145](0) g/mol Electron configuration [Xe] 4f5 6s2 Electrons per shell 2, 8, 18, 23, 8, 2 Physical properties Phase solid Density (near r. ... This article is about the chemical element. ... General Name, Symbol, Number thorium, Th, 90 Chemical series Actinides Group, Period, Block n/a, 7, f Appearance silvery white Standard atomic weight 232. ...


All chemical matter consists of these elements. New elements of higher atomic number are discovered from time to time, as products of artificial nuclear reactions. It has been suggested that this article or section be merged into Chemical element. ... In nuclear physics, a nuclear reaction is a process in which two nuclei or nuclear particles collide to produce products different from the initial particles. ...

Contents

History

Several ancient philosophies used a set of archetypal classical elements to explain patterns in nature. The term 'element' was originally used to refer to a state of matter (solid/earth, liquid/water, gas/air, and plasma/fire) or a phase of matter (as in the Chinese Wu Xing), rather than the chemical elements of modern science. The Greek, Indian (Tattva and Mahābhūta) and Japanese (go dai) traditions essentially had the same five elements: Air, Earth, Fire, Water and Aether. Image File history File links Size of this preview: 487 × 599 pixelsFull resolution (1067 × 1312 pixel, file size: 89 KB, MIME type: image/png) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Chemical element User:Sadi Carnot/Image... Image File history File links Size of this preview: 487 × 599 pixelsFull resolution (1067 × 1312 pixel, file size: 89 KB, MIME type: image/png) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Chemical element User:Sadi Carnot/Image... Mendeleyevs portrait by Ilya Repin. ... The Periodic Table redirects here. ... For other uses, see Philosophy (disambiguation). ... Many ancient philosophies used a set of archetypal classical elements to explain patterns in nature. ... This article is about the physical universe. ... A state of matter is a class of materials, usually solid, liquid, and gas. ... In the physical sciences, a phase is a set of states of a macroscopic physical system that have relatively uniform chemical composition and physical properties (i. ... Bön Hinduism (Tattva) and Buddhism (MahābhÅ«ta) Prithvi / Bhumi — Earth Ap / Jala — Water Vayu / Pavan — Air / Wind Agni / Tejas — Fire Akasha — Aether Japanese (Godai) Earth (地) Water (æ°´) Air / Wind (風) Fire (火) Void / Sky / Heaven (空) Chinese (Wu Xing) In traditional Chinese philosophy, natural phenomena can be classified into the Wu Xing... According to the Indian school of Samkhya philosophy, the Tattva are a way of directly experiencing the 5 alchemical elements. ... Chinese Wood (木) | Fire (火) | Earth (土) | Metal (金) | Water (æ°´) Hinduism and Buddhism The Panchamahabhuta or The Panchatattva (The Five Great Elements) Vayu/Pavan (Air/Wind) Agni/Tejas (Fire) Akasha (Aether) Prithvi/Bhumi (Earth) Ap/Jala (Water) MahābhÅ«ta is Pāli for the Great Elements. ... Chinese Wood (木) | Fire (火) | Earth (土) | Metal (金) | Water (æ°´) Hinduism The Panchamahabhuta (five great elements) Prithvi/Bhumi (Earth) Ap/Jala (Water) Agni/Tejas (Fire) Vayu/Pavan (Air/Wind) Akasha (Aether) Japan imported the different concepts of five elements from China and from Buddhism. ... . Bön . Hinduism (Tattva) and Buddhism (MahābhÅ«ta) Prithvi / Bhumi — Earth Ap / Jala — Water Vayu / Pavan — Air / Wind Agni / Tejas — Fire Akasha — Aether . ... . Bön . Hinduism (Tattva) and Buddhism (MahābhÅ«ta) Prithvi / Bhumi — Earth Ap / Jala — Water Vayu / Pavan — Air / Wind Agni / Tejas — Fire Akasha — Aether . ... . Bön . Hinduism (Tattva) and Buddhism (MahābhÅ«ta) Prithvi / Bhumi — Earth Ap / Jala — Water Vayu / Pavan — Air / Wind Agni / Tejas — Fire Akasha — Aether . ... Chinese Wood (木) | Fire (火) Earth (土) | Metal (金) | Water (æ°´) Japanese Earth (地) | Water (æ°´) | Fire (火) | Air / Wind (風) | Void / Sky / Heaven (空) Hinduism and Buddhism Vayu / Pavan — Air / Wind Agni / Tejas — Fire Akasha — Aether Prithvi / Bhumi — Earth Ap / Jala — Water Water has been important to all peoples of the earth, and it is rich in spiritual tradition. ... Hinduism (Tattva) and Buddhism (MahābhÅ«ta) Vayu / Pavan — Air / Wind Agni/Tejas — Fire Akasha — Aether Prithvi / Bhumi — Earth Ap / Jala — Water Chinese (Wu Xing) Japanese (Godai) Earth (地) | Water (æ°´) | Fire (火) | Air / Wind (風) | Void / Sky / Heaven (空) Bön Māori According to ancient and medieval science, Aether (Greek αἰθήρ, aithÄ“r[1...


The term 'elements' (stoicheia) was first used by the Greek philosopher Plato in about 360 BCE, in his dialogue Timaeus, which includes a discussion of the composition of inorganic and organic bodies and is a rudimentary treatise on chemistry. Plato assumed that the minute particle of each element corresponded to one of the regular polyhedra: tetrahedron (fire), octahedron (air), icosahedron (water), and cube (earth).[3] For other uses, see Plato (disambiguation). ... Timaeus (Greek: Τίμαιος, Timaios) is a theoretical treatise of Plato in the form of a Socratic dialogue, written circa 360 BC. The work puts forward speculation on the nature of the physical world. ... In mathematics, there are three related meanings of the term polyhedron: in the traditional meaning it is a 3-dimensional polytope, and in a newer meaning that exists alongside the older one it is a bounded or unbounded generalization of a polytope of any dimension. ... For the academic journal, see Tetrahedron (journal). ... An octahedron (plural: octahedra) is a polyhedron with eight faces. ... [Etymology: 16th century: from Greek eikosaedron, from eikosi twenty + -edron -hedron], icosahedral adjective An icosahedron noun (plural: -drons, -dra ) is any polyhedron having 20 faces, but usually a regular icosahedron is implied, which has equilateral triangles as faces. ... A cube[1] is a three-dimensional solid object bounded by six square faces, facets or sides, with three meeting at each vertex. ...


Adding to the four elements of the Greek philosopher Empedocles, in about 350 BC, Aristotle also used the term "element" and conceived of a fifth element called "quintessence", which formed the heavens. Aristotle defined an element as: Empedocles (Greek: , ca. ... For other uses, see Aristotle (disambiguation). ... Hinduism (Tattva) and Buddhism (Mahābhūta) Vayu / Pavan — Air / Wind Agni/Tejas — Fire Akasha — Aether Prithvi / Bhumi — Earth Ap / Jala — Water Chinese (Wu Xing) Japanese (Godai) Earth (地) | Water (水) | Fire (火) | Air / Wind (風) | Void / Sky / Heaven (空) Bön Māori According to ancient and medieval science, Aether (Greek αἰθήρ, aithēr[1...

Element – one of those bodies into which other bodies can be decomposed and which itself is not capable of being divided into other.[4]

Building on the theory in circa 790, Arabian chemist and alchemist, Jabir ibn Hayyan (Geber), postulated that metals were formed out of two elements: sulphur, ‘the stone which burns’, which characterized the principle of combustibility, and mercury, which contained the idealized principle of metallic properties.[5] Shortly thereafter, this evolved into the Arabic concept of the three principles: sulphur giving flammability or combustion, mercury giving volatility and stability, and salt giving solidity. Jabir ibn Hayyan and Geber were also pen names of an anonymous 14th century Spanish alchemist: see Pseudo-Geber. ... This article is about metallic materials. ... This article is about the chemical element. ... This article is about the element. ... This article is about the term salt as referred to in chemistry. ...


In the 10th century, Persian physician and alchemist Muhammad ibn Zakarīya Rāzi (Rhazes) wrote the Doubts concerning Galen, in which he refuted both the Galenic medical theory of four humours and the underlying ancient concept of four classical elements. He carried out an experiment which would upset these theories by inserting a liquid with a different temperature into a body resulting in an increase or decrease of bodily heat, which resembled the temperature of that particular fluid. Razi noted particularly that a warm drink would heat up the body to a degree much higher than its own natural temperature, thus the drink would trigger a response from the body, rather than transferring only its own warmth or coldness to it. Razi's chemical experiments suggested other qualities of matter, such as "oiliness" and "sulfurousness", or inflammability and salinity, which were not readily explained by the traditional fire, water, earth and air division of elements.[6] In the history of medicine, Islamic medicine or Arabic medicine refers to medicine developed in the medieval Islamic civilisation and written in Arabic, the lingua franca of the Islamic civilization. ... For other uses, see Razi. ... For other uses, see Galen (disambiguation). ... This article is about humors in Greco-Roman medicine. ... In the scientific method, an experiment (Latin: ex- periri, of (or from) trying) is a set of observations performed in the context of solving a particular problem or question, to retain or falsify a hypothesis or research concerning phenomena. ... Synthetic motor oil being poured. ... This article is about the chemical element. ... A symbol for inflammable chemicals Inflammability is the ease with which a substance will ignite, causing fire or combustion. ... Annual mean sea surface salinity for the World Ocean. ...


In 1524, Swiss chemist Paracelsus adopted Aristotle’s four element theory, but reasoned that they appeared in bodies as Geber’s three principles. Paracelsus saw these principles as fundamental, and justified them by recourse to the description of how wood burns in fire. Mercury included the cohesive principle, so that when it left in smoke the wood fell apart. Smoke represented the volatility (the mercury principle), the heat-giving flames represented flammability (sulphur), and the remnant ash represented solidity (salt).[5] Presumed portrait of Paracelsus, attributed to the school of Quentin Matsys. ...


In 1669, German physician and chemist Johann Becher published his Physica Subterranea. In modification on the ideas of Paracelsus, he argued that the constituents of bodies are air, water, and three types of earth: terra fluida, the mercurial element, which contributes fluidity and volatility; terra lapida, the solidifying element, which produces fusibility or the binding quality; and terra pinguis, the fatty element, which gives material substance its oily and combustible qualities.[7] These three earths correspond with Geber’s three principles. A piece of wood, for example, according to Becher, is composed of ash and terra pinguis; when the wood is burnt, the terra pinguis is released, leaving the ash. In other words, in combustion the fatty earth burns away. J.J. Becher Johann Joachim Becher (May 6, 1635 – October 1682), was a German physician, alchemist, precursor of Chemistry, scholar and adventurer. ...


In 1661, Robert Boyle showed that there were more than just four classical elements as the ancients had assumed.[8] The first modern list of chemical elements was given in Antoine Lavoisier's 1789 Elements of Chemistry, which contained thirty-three elements, including light and caloric. By 1818, Jöns Jakob Berzelius had determined atomic weights for forty-five of the forty-nine accepted elements. Dmitri Mendeleev had sixty-six elements in his periodic table of 1869. For the American art director and production designer, see Robert F. Boyle Robert Boyle (25 January 1627 – 30 December 1691) was a natural philosopher, chemist, physicist, inventor, and early gentleman scientist, noted for his work in physics and chemistry. ... Many ancient philosophies used a set of archetypal classical elements to explain patterns in nature. ... Lavoisier redirects here. ... For other uses, see Light (disambiguation). ... Friherre Jöns Jakob Berzelius (August 20, 1779 – August 7, 1848) was a Swedish chemist. ... Portrait of Dmitri Mendeleev by Ilya Repin (Russian: , Dmitri Ivanovich Mendeleev  ) (8 February [O.S. 27 January] 1834 in Tobolsk – 2 February [O.S. 20 January] 1907 in Saint Petersburg), was a Russian chemist and inventor. ... The Periodic Table redirects here. ...


From Boyle until the early 20th century, an element was defined as a pure substance that cannot be decomposed into any simpler substance.[8] Put another way, a chemical element cannot be transformed into other chemical elements by chemical processes. In 1913, Henry Moseley discovered that the physical basis of the atomic number of the atom was its nuclear charge, which eventually led to the current definition. The current definition also avoids some ambiguities due to isotopes and allotropes. Water and steam are two different forms of the same chemical substance A chemical substance is a material with a definite chemical composition. ... For other uses, see Chemistry (disambiguation). ... This article is about the physicist; for the naturalist see Henry Nottidge Moseley Henry Moseley at work. ... Isotopes are atoms of a chemical element whose nuclei have the same atomic number, Z, but different atomic weights, A. The word isotope, meaning at the same place, comes from the fact that isotopes are located at the same place on the periodic table. ... Allotropy (Gr. ...


By 1919, there were seventy-two known elements.[9] In 1955, element 101 was discovered and named mendelevium in honor of Mendeleev, the first to arrange the elements in a periodic manner. In October 2006, the synthesis of element 118 was reported; however, element 117 has not yet been created in the laboratory. General Name, Symbol, Number mendelevium, Md, 101 Chemical series actinides Group, Period, Block n/a, 7, f Appearance unknown, probably silvery white or metallic gray Atomic mass (258) g·mol−1 Electron configuration [Rn] 5f13 7s2 Electrons per shell 2, 8, 18, 32, 31, 8, 2 Physical properties Phase solid...


Description

The lightest elements are hydrogen and helium, both created by Big Bang nucleosynthesis during the first 20 minutes of the universe[10] in a ratio of around 3:1 by mass (approximately 12:1 by number of atoms). Almost all other elements found in nature, including some further hydrogen and helium created since then, were made by various natural or (at times) artificial methods of nucleosynthesis, including occasionally by activities such as nuclear fission. This article is about the chemistry of hydrogen. ... General Name, symbol, number helium, He, 2 Chemical series noble gases Group, period, block 18, 1, s Appearance colorless Standard atomic weight 4. ... In cosmology, Big Bang nucleosynthesis (or primordial nucleosynthesis) refers to the production of nuclei other than H-1, the normal, light hydrogen, during the early phases of the universe, shortly after the Big Bang. ... This box:      A graphical timeline is available here: Graphical timeline of the Big Bang This timeline of the Big Bang describes the events according to the scientific theory of the Big Bang, using the cosmological time parameter of comoving coordinates. ... This article is about the mathematical concept. ... Nucleosynthesis is the process of creating new atomic nuclei from preexisting nucleons (protons and neutrons). ... For the generation of electrical power by fission, see Nuclear power plant. ...


As of 2006, there are 117 known elements (in this context, "known" means observed well enough, even from just a few decay products, to have been differentiated from any other element).[11][12] Of these 117 elements, 94 occur naturally on Earth. Six of these occur in extreme trace quantities: technetium, atomic number 43; promethium, number 61; astatine, number 85; francium, number 87; neptunium, number 93; and plutonium, number 94. These 94 elements, and also possibly element 98 californium, have been detected in the universe at large, in the spectra of stars and also supernovae, where short-lived radioactive elements are newly being made. General Name, Symbol, Number technetium, Tc, 43 Chemical series transition metals Group, Period, Block 7, 5, d Appearance silvery gray metal Standard atomic weight [98](0) g·mol−1 Electron configuration [Kr] 4d5 5s2 Electrons per shell 2, 8, 18, 13, 2 Physical properties Phase solid Density (near r. ... General Name, Symbol, Number promethium, Pm, 61 Chemical series lanthanides Group, Period, Block n/a, 6, f Appearance metallic Atomic mass [145](0) g/mol Electron configuration [Xe] 4f5 6s2 Electrons per shell 2, 8, 18, 23, 8, 2 Physical properties Phase solid Density (near r. ... General Name, Symbol, Number astatine, At, 85 Chemical series halogens Group, Period, Block 17, 6, p Appearance metallic (presumed) Standard atomic weight (210) g·mol−1 Electron configuration [Xe] 4f14 5d10 6s2 6p5 Electrons per shell 2, 8, 18, 32, 18, 7 Physical properties Phase solid Melting point 575 K... General Name, Symbol, Number francium, Fr, 87 Chemical series alkali metals Group, Period, Block 1, 7, s Appearance metallic Standard atomic weight (223) g·mol−1 Electron configuration [Rn] 7s1 Electrons per shell 2, 8, 18, 32, 18, 8, 1 Physical properties Phase  ? solid Density (near r. ... General Name, Symbol, Number neptunium, Np, 93 Chemical series actinides Group, Period, Block n/a, 7, f Appearance silvery metallic Standard atomic weight (237) g·mol−1 Electron configuration [Rn] 5f4 6d1 7s2 Electrons per shell 2, 8, 18, 32, 22, 9, 2 Physical properties Phase solid Density (near r. ... This article is about the radioactive element. ... General Name, Symbol, Number californium, Cf, 98 Chemical series actinides Group, Period, Block n/a, 7, f Appearance silvery Standard atomic weight (251) g·mol−1 Electron configuration [Rn] 5f10 7s2 Electrons per shell 2, 8, 18, 32, 28, 8, 2 Physical properties Phase solid Density (near r. ...


The remaining 22 elements not found on Earth or in astronomical spectra have been derived artificially. All of the elements that are derived solely through artificial means are radioactive with very short half-lives; if any atoms of these elements were present at the formation of Earth, they are extremely likely to have already decayed, and if present in novae, have been in quantities too small to have been noted. Technetium was the first purportedly non-naturally occurring element to be synthesized, in 1937, although trace amounts of technetium have since been found in nature, and the element may have been discovered naturally in 1925. This pattern of artificial production and later natural discovery has been repeated with several other radioactive naturally occurring trace elements. Half-Life For a quantity subject to exponential decay, the half-life is the time required for the quantity to fall to half of its initial value. ... General Name, Symbol, Number technetium, Tc, 43 Chemical series transition metals Group, Period, Block 7, 5, d Appearance silvery gray metal Standard atomic weight [98](0) g·mol−1 Electron configuration [Kr] 4d5 5s2 Electrons per shell 2, 8, 18, 13, 2 Physical properties Phase solid Density (near r. ...


Lists of the elements by name, by symbol, by atomic number, by density, by melting point, and by boiling point as well as Ionization energies of the elements are available. The most convenient presentation of the elements is in the periodic table, which groups elements with similar chemical properties together. This is a list of chemical elements, sorted by name and color coded according to type of element. ... Categories: Chemical elements ... This is a list of the chemical elements, sorted by density measured at standard temperature and pressure. ... This is a list of the chemical elements, sorted by melting point measured at normal pressure. ... This is a list of the chemical elements, sorted by boiling point measured at normal pressure. ... These tables list the ionization energy in kJ/mol necessary to remove an electron from a neutral atom (first energy), respectively from a singly, doubly, etc. ... The Periodic Table redirects here. ...


Atomic number

The atomic number of an element, Z, is equal to the number of protons which defines the element. For example, all carbon atoms contain 6 protons in their nucleus; so the atomic number "Z" of carbon is 6. Carbon atoms may have different numbers of neutrons, which are known as isotopes of the element. See also: List of elements by atomic number In chemistry and physics, the atomic number (also known as the proton number) is the number of protons found in the nucleus of an atom. ... For other uses, see Carbon (disambiguation). ... The nucleus of an atom is the very small dense region, of positive charge, in its centre consisting of nucleons (protons and neutrons). ... For other uses, see Isotope (disambiguation). ...


The number of protons in the atomic nucleus also determines its electric charge, which in turn determines the electrons of the atom in its non-ionized state. This in turn (by means of the Pauli exclusion principle) determines the atom's various chemical properties. So all carbon atoms, for example, ultimately have identical chemical properties because they all have the same number of protons in their nucleus, and therefore have the same atomic number. It is for this reason that atomic number rather than mass number (or atomic weight) is considered the identifying characteristic of an element. This box:      Electric charge is a fundamental conserved property of some subatomic particles, which determines their electromagnetic interaction. ... For other uses, see Electron (disambiguation). ... Ionization is the physical process of converting an atom or molecule into an ion by changing the difference between the number of protons and electrons. ... The Pauli exclusion principle is a quantum mechanical principle formulated by Wolfgang Pauli in 1925. ... The phrase chemical property is context-dependent, but generally refers to a materials quality which becomes evident during a chemical reaction; this is, which can only be established by changing a substances chemical identity. ... The mass number (A), also called atomic mass number (not to be confused with atomic number (Z) which denotes the number of protons in a nucleus) or nucleon number, is the number of nucleons (protons and neutrons) in an atomic nucleus. ... ...


Atomic mass

The mass number of an element, A, is the number of nucleons (protons and neutrons) in the atomic nucleus. Different isotopes of a given element are distinguished by their mass numbers, which are conventionally written as a super-index on the left hand side of the atomic symbol (e.g., 238U). The mass number (A), also called atomic mass number (not to be confused with atomic number (Z) which denotes the number of protons in a nucleus) or nucleon number, is the number of nucleons (protons and neutrons) in an atomic nucleus. ... Nucleon is the common name used in nuclear chemistry to refer to a neutron or a proton, the components of an atoms nucleus. ...


The relative atomic mass of an element is the average of the atomic masses of all the chemical element's isotopes as found in a particular environment, weighted by isotopic abundance, relative to the atomic mass unit (u). This number may be a fraction which is not close to a whole number, due to the averaging process. On the other hand, the atomic mass of a pure isotope is quite close to its mass number. Whereas the mass number is a natural (or whole) number, the atomic mass of a single isotope is a real number which is close to a natural number. In general, it differs slightly from the mass number as the mass of the protons and neutrons is not exactly 1 u, the electrons also contribute slightly to the atomic mass, and because of the nuclear binding energy. For example, the mass of 19F is 18.9984032 u. The only exception to the atomic mass of an isotope not being a natural number is 12C, which has a mass of exactly 12, due to the definition of u (it is fixed as 1/12th of the mass of a free carbon-12 atom, exactly). In reference to a certain isotope of a chemical element, atomic mass (though also called relative atomic mass and atomic weight) is the mass of one atom of the isotope expressed in units (atomic mass unit, amu) such that the carbon-12 isotope has an atomic mass of exactly 12. ... The unified atomic mass unit (u), or dalton (Da), is a small unit of mass used to express atomic and molecular masses. ... Binding energy is the energy required to disassemble a whole into separate parts. ...


Isotopes

Isotopes are atoms of the same element (that is, with the same number of protons in their atomic nucleus), but having different numbers of neutrons. Most (66 of 94) naturally occurring elements have more than one stable isotope. Thus, for example, there are three main isotopes of carbon. All carbon atoms have 6 protons in the nucleus, but they can have either 6, 7, or 8 neutrons. Since the mass numbers of these are 12, 13 and 14 respectively, the three isotopes of carbon are known as carbon-12, carbon-13, and carbon-14, often abbreviated to 12C, 13C, and 14C. Carbon in everyday life and in chemistry is a mixture of 12C, 13C, and 14C atoms. For other uses, see Isotope (disambiguation). ... This article or section does not adequately cite its references or sources. ... For other uses, see Carbon (disambiguation). ... For other uses, see Chemistry (disambiguation). ...


All three of the isotopes of carbon have the same chemical properties. But they have different nuclear properties. In this example, carbon-12 and carbon-13 are stable atoms, but carbon-14 is unstable; it is slightly radioactive, decaying over time into other elements. Carbon-14 is the radioactive isotope of carbon discovered February 27, 1940, by Martin Kamen and Sam Ruben. ... Radioactive decay is the set of various processes by which unstable atomic nuclei (nuclides) emit subatomic particles. ...


Like carbon, some isotopes of various elements are radioactive and decay into other elements upon radiating an alpha or beta particle. For certain elements, all their isotopes are radioactive isotopes: specifically the elements without any stable isotopes are technetium (atomic number 43), promethium (atomic number 61), and all observed elements with atomic numbers greater than 82. Isotopes are atoms of a chemical element whose nuclei have the same atomic number, Z, but different atomic weights, A. The word isotope, meaning at the same place, comes from the fact that isotopes are located at the same place on the periodic table. ... Radioactive decay is the set of various processes by which unstable atomic nuclei (nuclides) emit subatomic particles. ... In chemistry and physics, the atomic number (Z) is the number of protons found in the nucleus of an atom. ...


Of the 80 elements with a stable isotope, 16 have only one stable isotope, and the mean number of stable isotopes for the 80 stable elements is 3.4 stable isotopes per element. The largest number of stable isotopes that occur for an element is 10 (for tin, element 50).


Allotropes

Some elements can be found as multiple elementary substances, known as allotropes, which differ in their structure and properties. For example, carbon can be found as diamond, which has a tetrahedral structure around each carbon atom; graphite, which has layers of carbon atoms with a hexagonal structure, and fullerenes, which have nearly spherical shapes. The ability for an element to exist in one of many structural forms is known as 'allotropy'. Allotropy (Gr. ... This article is about the mineral. ... For other uses, see Graphite (disambiguation). ... The Icosahedral Fullerene C540 C60 and C-60 redirect here. ...


Standard state

The standard state, or reference state, of an element is defined as its thermodynamically most stable state at 1 bar at a given temperature (typically at 298.15 K). In thermochemistry, an element is defined to have an enthalpy of formation of zero in its standard state. For example, the reference state for carbon is graphite, because it is more stable than the other allotropes. The plimsoll symbol as used in shipping In chemistry, the standard state of a material is its state at 1 bar (100 kilopascals exactly). ... The world’s first ice-calorimeter, used in the winter of 1782-83, by Antoine Lavoisier and Pierre-Simon Laplace, to determine the heat evolved in various chemical changes; calculations which were based on Joseph Black’s prior discovery of latent heat. ... The standard enthalpy of formation or standard heat of formation of a compound is the change of enthalpy that accompanies the formation of 1 mole of a substance in its standard state from its constituent elements in their standard states (the most stable form of the element at 1 atmosphere...


Nomenclature

The naming of elements precedes the atomic theory of matter, although at the time it was not known which chemicals were elements and which compounds. When it was learned, existing names (e.g., gold, mercury, iron) were kept in most countries, and national differences emerged over the names of elements either for convenience, linguistic niceties, or nationalism. For example, the Germans use "Wasserstoff" for "hydrogen" and "Sauerstoff" for "oxygen", while English and some romance languages use "sodium" for "natrium" and "potassium" for "kalium", and the French, Greeks, Portuguese and Poles prefer "azote/azot/azoto" for "nitrogen". The English language is a West Germanic language that originates in England. ... The Romance languages, also called Romanic languages, are a subfamily of the Italic languages, specifically the descendants of the Vulgar Latin dialects spoken by the common people evolving in different areas after the break-up of the Roman Empire. ...


But for international trade, the official names of the chemical elements both ancient and recent are decided by the International Union of Pure and Applied Chemistry, which has decided on a sort of international English language. That organization has recently prescribed that "aluminium" and "caesium" take the place of the US spellings "aluminum" and "cesium", while the US "sulfur" takes the place of the British "sulphur". But chemicals which are practicable to be sold in bulk within many countries, however, still have national names, and those which do not use the Latin alphabet cannot be expected to use the IUPAC name. According to IUPAC, the full name of an element is not capitalized, even if it is derived from a proper noun such as the elements californium or einsteinium (unless it would be capitalized by some other rule). Isotopes of chemical elements are also uncapitalized if written out: carbon-12 or uranium-235. A table of chemical elements ordered by atomic number. ... IUPAC logo The International Union of Pure and Applied Chemistry (IUPAC) (Pronounced as eye-you-pack) is an international non-governmental organization established in 1919 devoted to the advancement of chemistry. ... Abcdefghijklmnopqrstuvwxyz redirects here. ... General Name, Symbol, Number californium, Cf, 98 Chemical series actinides Group, Period, Block n/a, 7, f Appearance silvery Standard atomic weight (251) g·mol−1 Electron configuration [Rn] 5f10 7s2 Electrons per shell 2, 8, 18, 32, 28, 8, 2 Physical properties Phase solid Density (near r. ... General Name, Symbol, Number einsteinium, Es, 99 Chemical series actinides Group, Period, Block n/a, 7, f Appearance unknown, probably silvery white or metallic gray Standard atomic weight (252) g·mol−1 Electron configuration [Rn] 5f11 7s2 Electrons per shell 2, 8, 18, 32, 29, 8, 2 Physical properties Phase... Capitalization (or capitalisation) is writing a word with its first letter as a majuscule (upper case letter) and the remaining letters in minuscules (lower case letters), in those writing systems which have a case distinction. ... Carbon 12 is a stable isotope of the element carbon. ... Uranium-235 is an isotope of uranium that differs from the elements other common isotope, uranium-238, by its ability to cause a rapidly expanding fission chain reaction. ...


In the second half of the twentieth century physics laboratories became able to produce nuclei of chemical elements that have a half life too short for them to remain in any appreciable amounts. These are also named by IUPAC, which generally adopts the name chosen by the discoverer. This can lead to the controversial question of which research group actually discovered an element, a question which delayed the naming of elements with atomic number of 104 and higher for a considerable time. (See element naming controversy). This article is about the computer game. ... The names for the chemical elements 104 to 109 were the subject of a major controversy starting in the 1960s which was finally resolved in 1997. ...


Precursors of such controversies involved the nationalistic namings of elements in the late nineteenth century. For example, lutetium was named in reference to Paris, France. The Germans were reluctant to relinquish naming rights to the French, often calling it cassiopeium. The British discoverer of niobium originally named it columbium, in reference to the New World. It was used extensively as such by American publications prior to international standardization. General Name, Symbol, Number lutetium, Lu, 71 Chemical series lanthanides Group, Period, Block n/a, 6, d Appearance silvery white Standard atomic weight 174. ... General Name, Symbol, Number niobium, Nb, 41 Chemical series transition metals Group, Period, Block 5, 5, d Appearance gray metallic Standard atomic weight 92. ... Frontispiece of Peter Martyr dAnghieras De orbe novo (On the New World). Carte dAmérique, Guillaume Delisle, 1722. ...


Chemical symbols

For the listing of current and not used Chemical symbols, and other symbols that look like chemical symbols, please see List of elements by symbol.

A chemical symbol is an abbreviation or short representation of the name of a chemical element. ... // This is a list of chemical elements by symbol, including the current signification used to identify the chemical elements as recognized by the International Union of Pure and Applied Chemistry, as well as proposed and historical signs. ...

Specific chemical elements

Before chemistry became a science, alchemists had designed arcane symbols for both metals and common compounds. These were however used as abbreviations in diagrams or procedures; there was no concept of atoms combining to form molecules. With his advances in the atomic theory of matter, John Dalton devised his own simpler symbols, based on circles, which were to be used to depict molecules. For other uses, see Alchemy (disambiguation). ... John Dalton John Dalton (September 6, 1766 – July 27, 1844) was an English chemist and physicist, born at Eaglesfield, near Cockermouth in Cumberland. ...


The current system of chemical notation was invented by Berzelius. In this typographical system chemical symbols are not used as mere abbreviations - though each consists of letters of the Latin alphabet - they are symbols intended to be used by peoples of all languages and alphabets. The first of these symbols were intended to be fully universal; since Latin was the common language of science at that time, they were abbreviations based on the Latin names of metals - Fe comes from Ferrum, Ag from Argentum. The symbols were not followed by a period (full stop) as abbreviations were. Later chemical elements were also assigned unique chemical symbols, based on the name of the element, but not necessarily in English. For example, sodium has the chemical symbol 'Na' after the Latin natrium. The same applies to "W" (wolfram) for tungsten, "Hg" (hydrargyrum) for mercury, "K" (kalium) for potassium, "Au" (aurum) for gold, "Pb" (plumbum) for lead, and "Sb" (stibium) for antimony. Friherre Jöns Jakob Berzelius (August 20, 1779 – August 7, 1848) was a Swedish chemist. ... Abcdefghijklmnopqrstuvwxyz redirects here. ... For other uses, see Latins and Latin (disambiguation). ... For sodium in the diet, see Salt. ... For other uses, see Tungsten (disambiguation). ... This article is about the element. ... General Name, symbol, number potassium, K, 19 Chemical series alkali metals Group, period, block 1, 4, s Appearance silvery white Standard atomic weight 39. ... GOLD refers to one of the following: GOLD (IEEE) is an IEEE program designed to garner more student members at the university level (Graduates of the Last Decade). ... General Name, Symbol, Number lead, Pb, 82 Chemical series Post-transition metals or poor metals Group, Period, Block 14, 6, p Appearance bluish gray Standard atomic weight 207. ... This article is about the element. ...


Chemical symbols are understood internationally when element names might need to be translated. There are sometimes differences; for example, the Germans have used "J" instead of "I" for iodine, so the character would not be confused with a roman numeral. The system of Roman numerals is a numeral system originating in ancient Rome, and was adapted from Etruscan numerals. ...


The first letter of a chemical symbol is always capitalized, as in the preceding examples, and the subsequent letters, if any, are always lower case (small letters).


General chemical symbols

There are also symbols for series of chemical elements, for comparative formulas. These are one capital letter in length, and the letters are reserved so they are not permitted to be given for the names of specific elements. For example, an "X" is used to indicate a variable group amongst a class of compounds (though usually a halogen), while "R" is used for a radical, meaning a compound structure such as a hydrocarbon chain. The letter "Q" is reserved for "heat" in a chemical reaction. "Y" is also often used as a general chemical symbol, although it is also the symbol of yttrium. "Z" is also frequently used as a general variable group. "L" is used to represent a general ligand in inorganic and organometallic chemistry. "M" is also often used in place of a general metal. This article is about the chemical series. ... In chemistry, radicals (often referred to as free radicals) are atomic or molecular species with unpaired electrons on an otherwise open shell configuration. ... General Name, Symbol, Number yttrium, Y, 39 Chemical series transition metals Group, Period, Block 3, 5, d Appearance silvery white Standard atomic weight 88. ... In chemistry, a ligand is an atom, ion, or molecule (see also: functional group) that generally donates one or more of its electrons through a coordinate covalent bond to, or shares its electrons through a covalent bond with, one or more central atoms or ions (these ligands act as a...


Isotope symbols

The three main isotopes of the element hydrogen are often written as H for protium, D for deuterium and T for tritium. This is in order to make it easier to use them in chemical equations, as it replaces the need to write out the mass number for each atom. It is written like this: This article is about the chemistry of hydrogen. ... Deuterium, also called heavy hydrogen, is a stable isotope of hydrogen with a natural abundance in the oceans of Earth of approximately one atom in 6500 of hydrogen (~154 PPM). ... Tritium (symbol T or ³H) is a radioactive isotope of hydrogen. ...


D2O (heavy water) Heavy water is dideuterium oxide, or D2O or 2H2O. It is chemically the same as normal water, H2O, but the hydrogen atoms are of the heavy isotope deuterium, in which the nucleus contains a neutron in addition to the proton found in the nucleus of any hydrogen atom. ...


Instead of writing it like this:


²H2O


The periodic table

The periodic table of the chemical elements is a tabular method of displaying the chemical elements. Although precursors to this table exist, its invention is generally credited to Russian chemist Dmitri Mendeleev in 1869. Mendeleev intended the table to illustrate recurring ("periodic") trends in the properties of the elements. The layout of the table has been refined and extended over time, as new elements have been discovered, and new theoretical models have been developed to explain chemical behavior. The Periodic Table redirects here. ... Portrait of Dmitri Mendeleev by Ilya Repin (Russian: , Dmitri Ivanovich Mendeleev  ) (8 February [O.S. 27 January] 1834 in Tobolsk – 2 February [O.S. 20 January] 1907 in Saint Petersburg), was a Russian chemist and inventor. ...


The periodic table is now ubiquitous within the academic discipline of chemistry, providing an extremely useful framework to classify, systematize and compare all the many different forms of chemical behavior. The table has also found wide application in physics, biology, engineering, and industry. The current standard table contains 117 confirmed elements as of January 27, 2008 (while element 118 has been synthesized, element 117 has not).


Abundance

During the early phases of the Big Bang, nucleosynthesis of hydrogen nuclei resulted in the production of hydrogen and helium isotopes, as well as very minuscule amounts (on the order of 10-10) of lithium and beryllium. There is argument about whether or not some boron was produced in the Big Bang, as it has been observed in some very young stars,[13] but no heavier elements than boron were produced. As a result, the primordial abundance of atoms consisted of roughly 75% 1H, 25% 4He, and 0.01% deuterium.[14] Subsequent enrichment of galactic halos occurred due to Stellar nucleosynthesis and Supernova nucleosynthesis.[15] However intergalactic space can still closely resemble the primordial abundance, unless it has been enriched by some means. The abundance of a chemical element measures how relatively common the element is, or how much of the element there is by comparison to all other elements. ... For other uses, see Big Bang (disambiguation). ... In cosmology, Big Bang nucleosynthesis (or primordial nucleosynthesis) refers to the production of nuclei other than H-1, the normal, light hydrogen, during the early phases of the universe, shortly after the Big Bang. ... Deuterium, also called heavy hydrogen, is a stable isotope of hydrogen with a natural abundance in the oceans of Earth of approximately one atom in 6500 of hydrogen (~154 PPM). ... Spiral galaxies have a typical structure related to their history. ... Cross section of a red giant showing nucleosynthesis and elements formed Stellar nucleosynthesis is the collective term for the nuclear reactions taking place in stars to build the nuclei of the heavier elements. ... Supernova nucleosynthesis refers to the production of new chemical elements inside supernovae. ... Intergalactic redirects here. ...


The following table shows the twelve most common elements in our galaxy (estimated spectroscopically), as measured in parts per million, by mass.[16] Nearby galaxies that have evolved along similar lines have a corresponding enrichment of elements heavier than hydrogen and helium. The more distant galaxies are being viewed as they appeared in the past, so their abundances of elements appear closer to the primordial mixture. As physical laws and processes appear common throughout the visible universe, however, it is expected that these galaxies will likewise have evolved similar abundances of elements. The deepest visible-light image of the cosmos. ...

Element Parts per million
by mass
Hydrogen 739,000
Helium 240,000
Oxygen 10,400
Carbon 4,600
Neon 1,340
Iron 1,090
Nitrogen 960
Silicon 650
Magnesium 580
Sulfur 440
Potassium 210
Nickel 100

This article is about the chemistry of hydrogen. ... General Name, symbol, number helium, He, 2 Chemical series noble gases Group, period, block 18, 1, s Appearance colorless Standard atomic weight 4. ... This article is about the chemical element and its most stable form, or dioxygen. ... For other uses, see Carbon (disambiguation). ... For other uses, see Neon (disambiguation). ... Fe redirects here. ... General Name, symbol, number nitrogen, N, 7 Chemical series nonmetals Group, period, block 15, 2, p Appearance colorless gas Standard atomic weight 14. ... Not to be confused with Silicone. ... General Name, symbol, number magnesium, Mg, 12 Chemical series alkaline earth metals Group, period, block 2, 3, s Appearance silvery white solid at room temp Standard atomic weight 24. ... This article is about the chemical element. ... General Name, symbol, number potassium, K, 19 Chemical series alkali metals Group, period, block 1, 4, s Appearance silvery white Standard atomic weight 39. ... For other uses, see Nickel (disambiguation). ...

Recently discovered element claims

The first transuranium element (element with atomic number greater than 92) discovered was neptunium in 1940. As of August 2007, only the elements up to 111, Roentgenium, have been confirmed as valid by IUPAC, while more or less reliable claims have been made for synthesis of elements 112, 113, 114, 115, 116 and 118. The heaviest element that is believed to have been synthesized to date is element 118, ununoctium, on October 9, 2006, by the Flerov Laboratory of Nuclear Reactions in Dubna, Russia.[17][18] This article needs additional references or sources to facilitate its verification. ... See also: List of elements by atomic number In chemistry and physics, the atomic number (also known as the proton number) is the number of protons found in the nucleus of an atom. ... General Name, Symbol, Number neptunium, Np, 93 Chemical series actinides Group, Period, Block n/a, 7, f Appearance silvery metallic Standard atomic weight (237) g·mol−1 Electron configuration [Rn] 5f4 6d1 7s2 Electrons per shell 2, 8, 18, 32, 22, 9, 2 Physical properties Phase solid Density (near r. ... General Name, Symbol, Number roentgenium, Rg, 111 Chemical series transition metals Group, Period, Block 11, 7, d Appearance unknown, probably yellow or orange metallic Atomic mass (284) g/mol Electron configuration perhaps [Rn] 5f14 6d10 7s1 (guess based on gold) Electrons per shell 2, 8, 18, 32, 32, 18, 1... The International Union of Pure and Applied Chemistry (IUPAC) is an international non-governmental organization devoted to the advancement of chemistry. ... General Name, Symbol, Number ununbium, Uub, 112 Chemical series transition metals Group, Period, Block 12, 7, d Appearance unknown, probably silvery white or metallic gray liquid Atomic mass (285) g/mol Electron configuration perhaps [Rn] 5f14 6d10 7s2 (guess based on mercury) Electrons per shell 2, 8, 18, 32, 32... General Name, Symbol, Number ununtrium, Uut, 113 Chemical series presumably poor metals Group, Period, Block 13, 7, p Appearance unknown, probably silvery white or metallic gray Atomic mass (284) g/mol Electron configuration perhaps [Rn] 5f14 6d10 7s2 7p1 (guess based on thallium) Electrons per shell 2, 8, 18, 32... General Name, Symbol, Number ununquadium, Uuq, 114 Chemical series presumably poor metals Group, Period, Block 14, 7, p Appearance unknown, probably silvery white or metallic gray Standard atomic weight [289] g·mol−1 Electron configuration perhaps [Rn] 5f14 6d10 7s2 7p2 (guess based on lead) Electrons per shell 2, 8... General Name, Symbol, Number ununpentium, Uup, 115 Group, Period, Block 15, 7, p Atomic mass (299) g·mol−1 Electron configuration perhaps [Rn] 5f14 6d10 7s2 7p3 (guess based on bismuth) Electrons per shell 2, 8, 18, 32, 32, 18, 5 CAS registry number 54085-64-2 Selected isotopes References... General Name, Symbol, Number ununhexium, Uuh, 116 Chemical series presumably poor metals Group, Period, Block 16, 7, p Appearance unknown, probably silvery white or metallic gray Atomic mass (302) g/mol Electron configuration perhaps [Rn] 5f14 6d10 7s2 7p4 (guess based on polonium) Electrons per shell 2, 8, 18, 32... General Name, Symbol, Number ununoctium, Uuo, 118 Chemical series noble gases Group, Period, Block 18, 7, p Appearance unknown, probably colorless Atomic mass predicted, (314) g/mol Electron configuration perhaps [Rn] 5f14 6d10 7s2 7p6 (guess based on radon) Electrons per shell 2, 8, 18, 32, 32, 18, 8 Phase... General Name, Symbol, Number ununoctium, Uuo, 118 Chemical series noble gases Group, Period, Block 18, 7, p Appearance unknown, probably colorless Atomic mass predicted, (314) g/mol Electron configuration perhaps [Rn] 5f14 6d10 7s2 7p6 (guess based on radon) Electrons per shell 2, 8, 18, 32, 32, 18, 8 Phase... Dubna is a small city located in central Russia, in the Taldomsky district of Moscow Oblast, approximately 125 km north of Moscow, on the banks of the Volga river. ...


Element 117, ununseptium, has not yet been created or discovered, although its place in the periodic table is preestablished. General Name, Symbol, Number ununseptium, Uus, 117 Chemical series presumably halogens Group, Period, Block 17, 7, p Appearance unknown, probably dark metallic Standard atomic weight predicted, (310) g·mol−1 Electron configuration perhaps [Rn] 5f14 6d10 7s2 7p5 (guess based on astatine) Electrons per shell 2, 8, 18, 32, 32...


According to Amnon Marinov and six other researchers element 122 has been detected naturally occurring in a thorium deposit.[19], this is the first Naturally occurring heavy element in more than 50 years. It has yet to be proved as it is still under confirmation by the university but could be a major development as previously all transuranic elements were artificial. Predicted properties Name, Symbol, Number Unbibium, Ubb, 122 Chemical series Superactinides Period, Block 8, f Appearance unknown; probably metallic, silvery white or gray Atomic weight [324] u Electron configuration p[Uuo] 7d28s2 e-s per energy level 2, 8, 18, 32, 34, 20, 8, 2 State of matter Presumably a...


See also

The abundance of a chemical element measures how relatively common the element is, or how much of the element there is by comparison to all other elements. ... A chemical compound is a substance consisting of two or more different elements chemically bonded together in a fixed proportion by mass. ... A chemical symbol is an abbreviation or short representation of the name of a chemical element. ... For other uses, see Chemistry (disambiguation). ... This article or section should be merged with Timeline of chemical element discovery The story of the discoveries of the chemical elements is presented here in chronological order. ... The Elements (1959) is a song by Tom Lehrer that recites the names of all the chemical elements that were known at the time of writing, up to number 102, nobelium. ... A fictional chemical substance is a chemical element, isotope, compound or mineral that exists only in works of fiction (usually fantasy or science fiction). ... The Goldschmidt Classification, developed by Victor Goldschmidt, is a geochemical classification which groups the chemical elements according to their preferred host phases into siderophile (iron loving), lithophile (silicate loving), chalcophile (sulphur loving), and atmophile (gas loving). ... 3-dimensional rendering of the theoretical Island of Stability. ... Categories: | | | | ... A table of chemical elements ordered by atomic number and color coded according to type of element. ... This is a list of chemical elements, sorted by name and color coded according to type of element. ... The Periodic Table redirects here. ... In chemistry, heavy transuranic elements receive a permanent trivial name and symbol only after their synthesis has been confirmed. ...

References

  1. ^ Compendium of Chemical Terminology, chemical element
  2. ^ A. Earnshaw, Norman Greenwood. Chemistry of the Elements, Second Edition. Butterworth-Heinemann, 1997
  3. ^[citation needed]Hillar, Marian (2004). The Problem of the Soul in Aristotle's De anima. NASA WMAP. Retrieved on 2006-08-10.
  4. ^ Partington, J.R. (1937). A Short History of Chemistry. New York: Dover Publications, Inc.. ISBN 0486659771. 
  5. ^ a b Strathern, Paul. (2000). Mendeleyev’s Dream – the Quest for the Elements. New York: Berkley Books.
  6. ^ G. Stolyarov II (2002), "Rhazes: The Thinking Western Physician", The Rational Argumentator, Issue VI
  7. ^ Partington, J.R. (1937). A Short History of Chemistry. New York: Dover Publications, Inc.
  8. ^ a b Boyle, Robert (1661). The Sceptical Chymist. 
  9. ^ Carey, George, W. (1914). The Chemistry of Human Life. 
  10. ^ Gaitskell, R (2006). "Evidence for Dark Matter". Physical Review C 74: timeline on page 10. doi:10.1103/PhysRevC.74.044602. Retrieved on 2008-10-08. 
  11. ^ Sanderson, Katherine (17 October 2006). Heaviest element made - again. nature@news.com. Nature (journal). Retrieved on 2006-10-19.
  12. ^ Phil Schewe and Ben Stein (17 October 2006). Elements 116 and 118 Are Discovered. Physics News Update. American Institute of Physics. Retrieved on 2006-10-19.
  13. ^ Hubble Observations Bring Some Surprises - New York Times
  14. ^ Wright, Edward L. (September 12, 2004). Big Bang Nucleosynthesis. UCLA Division of Astronomy. Retrieved on 2007-02-22.
  15. ^ G. Wallerstein, I. Iben Jr., P. Parker, A. M. Boesgaard, G. M. Hale, A. E. Champagne, C. A. Barnes, F. KM-dppeler, V. V. Smith, R. D. Hoffman, F. X. Timmes, C. Sneden, R.N. Boyd, B.S. Meyer, D.L. Lambert (1999). "Synthesis of the elements in stars: forty years of progress" (pdf). Reviews of Modern Physics 69 (4): 995–1084. doi:10.1103/RevModPhys.69.995. Retrieved on 2006-08-04. 
  16. ^ Croswell, Ken (February 1996). Alchemy of the Heavens. Anchor. ISBN 0-385-47214-5. 
  17. ^ Phil Schewe and Ben Stein (17 October 2006). Elements 116 and 118 Are Discovered. Physics News Update. American Institute of Physics. Retrieved on 2006-10-19.
  18. ^ Oganessian, Yu. Ts.; Utyonkov, V.K.; Lobanov, Yu.V.; Abdullin, F.Sh.; Polyakov, A.N.; Sagaidak, R.N.; Shirokovsky, I.V.; Tsyganov, Yu.S.; Voinov, Yu.S.; Gulbekian, G.G.; Bogomolov, S.L.; B. N. Gikal, A. N. Mezentsev, S. Iliev; Subbotin, V.G.; Sukhov, A.M.; Subotic, K; Zagrebaev, V.I.; Vostokin, G.K.; Itkis, M. G.; Moody, K.J; Patin, J.B.; Shaughnessy, D.A.; Stoyer, M.A.; Stoyer, N.J.; Wilk, P.A.; Kenneally, J.M.; Landrum, J.H.; Wild, J.H.; and Lougheed, R.W. (2006-10-09). "Synthesis of the isotopes of elements 118 and 116 in the 249Cf and 245Cm+48Ca fusion reactions". Physical Review C 74 (4): 044602. doi:10.1103/PhysRevC.74.044602. Retrieved on 2006-10-16. 
  19. ^ Marinov, A.; Rodushkin, I.; Kolb, D.; Pape, A.; Kashiv, Y.; Brandt, R.; Gentry, R. V.; Miller, H. W. (2008). "Evidence for a long-lived superheavy nucleus with atomic mass number A=292 and atomic number Z=~122 in natural Th". arXiv.org 74: 044602. doi:10.1103/PhysRevC.74.044602. Retrieved on 2008-04-28. 
  • E.R. Scerri, The Periodic Table, Its Story and Its Significance, Oxford University Press, NY, 2007.

Compendium of Chemical Terminology (ISBN 0-86542-684-8) is a book published by IUPAC containing internationally accepted definitions for terms in chemistry. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 222nd day of the year (223rd in leap years) in the Gregorian calendar. ... For the American art director and production designer, see Robert F. Boyle Robert Boyle (25 January 1627 – 30 December 1691) was a natural philosopher, chemist, physicist, inventor, and early gentleman scientist, noted for his work in physics and chemistry. ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... 2008 (MMVIII) is the current year, a leap year that started on Tuesday of the Common Era (or Anno Domini), in accordance with the Gregorian calendar. ... is the 281st day of the year (282nd in leap years) in the Gregorian calendar. ... is the 290th day of the year (291st in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... Nature is a prominent scientific journal, first published on 4 November 1869. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 292nd day of the year (293rd in leap years) in the Gregorian calendar. ... is the 290th day of the year (291st in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... The American Institute of Physics (AIP) is a professional body representing American physicists and publishing physics related journals. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 292nd day of the year (293rd in leap years) in the Gregorian calendar. ... is the 255th day of the year (256th in leap years) in the Gregorian calendar. ... Year 2004 (MMIV) was a leap year starting on Thursday of the Gregorian calendar. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 53rd day of the year in the Gregorian calendar. ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 216th day of the year (217th in leap years) in the Gregorian calendar. ... is the 290th day of the year (291st in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... The American Institute of Physics (AIP) is a professional body representing American physicists and publishing physics related journals. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 292nd day of the year (293rd in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 282nd day of the year (283rd in leap years) in the Gregorian calendar. ... Physical Review is one of the oldest and most-respected scientific journals publishing research on all aspects of physics. ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 289th day of the year (290th in leap years) in the Gregorian calendar. ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... 2008 (MMVIII) is the current year, a leap year that started on Tuesday of the Common Era (or Anno Domini), in accordance with the Gregorian calendar. ... is the 118th day of the year (119th in leap years) in the Gregorian calendar. ...

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Chemistry: WebElements Periodic Table (426 words)
The periodic "law" of chemistry recognises that many properties of the chemical elements are periodic functions of their atomic number (the number of protons within the element's atomic nucleus).
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A group of elements called metalloids, intermediate in properties between the metals and the nonmetals, are sometimes considered a separate class.
When the elements are arranged in the order of their atomic numbers (a number proportional to the net positive charge on the nucleus of an atom of an element), elements of similar physical and chemical properties occur at specific intervals (see Periodic Law).
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