A report on Atom and Chemical element

Atoms and molecules as depicted in John Dalton's A New System of Chemical Philosophy vol. 1 (1808)
The chemical elements ordered in the periodic table
The Geiger–Marsden experiment:
Left: Expected results: alpha particles passing through the plum pudding model of the atom with negligible deflection.
Right: Observed results: a small portion of the particles were deflected by the concentrated positive charge of the nucleus.
Estimated distribution of dark matter and dark energy in the universe. Only the fraction of the mass and energy in the universe labeled "atoms" is composed of chemical elements.
The Bohr model of the atom, with an electron making instantaneous "quantum leaps" from one orbit to another with gain or loss of energy. This model of electrons in orbits is obsolete.
Periodic table showing the cosmogenic origin of each element in the Big Bang, or in large or small stars. Small stars can produce certain elements up to sulfur, by the alpha process. Supernovae are needed to produce "heavy" elements (those beyond iron and nickel) rapidly by neutron buildup, in the r-process. Certain large stars slowly produce other elements heavier than iron, in the s-process; these may then be blown into space in the off-gassing of planetary nebulae
The binding energy needed for a nucleon to escape the nucleus, for various isotopes
Abundances of the chemical elements in the Solar System. Hydrogen and helium are most common, from the Big Bang. The next three elements (Li, Be, B) are rare because they are poorly synthesized in the Big Bang and also in stars. The two general trends in the remaining stellar-produced elements are: (1) an alternation of abundance in elements as they have even or odd atomic numbers (the Oddo-Harkins rule), and (2) a general decrease in abundance as elements become heavier. Iron is especially common because it represents the minimum energy nuclide that can be made by fusion of helium in supernovae.
A potential well, showing, according to classical mechanics, the minimum energy V(x) needed to reach each position x. Classically, a particle with energy E is constrained to a range of positions between x1 and x2.
Mendeleev's 1869 periodic table: An experiment on a system of elements. Based on their atomic weights and chemical similarities.
3D views of some hydrogen-like atomic orbitals showing probability density and phase (g orbitals and higher are not shown)
Dmitri Mendeleev
This diagram shows the half-life (T½) of various isotopes with Z protons and N neutrons.
Henry Moseley
These electron's energy levels (not to scale) are sufficient for ground states of atoms up to cadmium (5s2 4d10) inclusively. Do not forget that even the top of the diagram is lower than an unbound electron state.
An example of absorption lines in a spectrum
Graphic illustrating the formation of a Bose–Einstein condensate
Scanning tunneling microscope image showing the individual atoms making up this gold (100) surface. The surface atoms deviate from the bulk crystal structure and arrange in columns several atoms wide with pits between them (See surface reconstruction).
Periodic table showing the origin of each element. Elements from carbon up to sulfur may be made in small stars by the alpha process. Elements beyond iron are made in large stars with slow neutron capture (s-process). Elements heavier than iron may be made in neutron star mergers or supernovae after the r-process.

An atom is the smallest unit of ordinary matter that forms a chemical element.

- Atom

A chemical element is a species of atoms that have a given number of protons in their nuclei, including the pure substance consisting only of that species.

- Chemical element
Atoms and molecules as depicted in John Dalton's A New System of Chemical Philosophy vol. 1 (1808)

29 related topics with Alpha

Overall

The Space Shuttle Main Engine burnt hydrogen with oxygen, producing a nearly invisible flame at full thrust.

Hydrogen

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The Space Shuttle Main Engine burnt hydrogen with oxygen, producing a nearly invisible flame at full thrust.
Depiction of a hydrogen atom with size of central proton shown, and the atomic diameter shown as about twice the Bohr model radius (image not to scale)
Hydrogen gas is colorless and transparent, here contained in a glass ampoule.
Phase diagram of hydrogen. The temperature and pressure scales are logarithmic, so one unit corresponds to a 10x change. The left edge corresponds to 105 Pa, which is about atmospheric pressure.
A sample of sodium hydride
Hydrogen discharge (spectrum) tube
Deuterium discharge (spectrum) tube
Antoine-Laurent de Lavoisier
Hydrogen emission spectrum lines in the visible range. These are the four visible lines of the Balmer series
NGC 604, a giant region of ionized hydrogen in the Triangulum Galaxy
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Hydrogen is the chemical element with the symbol H and atomic number 1.

For the most common isotope of hydrogen (symbol 1H) each atom has one proton, one electron, and no neutrons.

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Periodic table

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3D views of some hydrogen-like atomic orbitals showing probability density and phase (g orbitals and higher are not shown)
Idealized order of shell-filling (most accurate for n  ≲ 4.)
Trend in atomic radii
Graph of first ionisation energies of the elements in electronvolts (predictions used for elements 105–118)
Trend in electron affinities
Flowing liquid mercury. Its liquid state at room temperature is a result of special relativity.
A periodic table colour-coded to show some commonly used sets of similar elements. The categories and their boundaries differ somewhat between sources. Alkali metals
 Alkaline earth metals
 Lanthanides
 Actinides
 Transition metals Other metals
 Metalloids
 Other nonmetals
 Halogens
 Noble gases
Mendeleev's 1869 periodic table
Mendeleev's 1871 periodic table
Dmitri Mendeleev
Henry Moseley
Periodic table of van den Broek
Glenn T. Seaborg
One possible form of the extended periodic table to element 172, suggested by Finnish chemist Pekka Pyykkö. Deviations from the Madelung order (8s < < 6f < 7d < 8p) begin to appear at elements 139 and 140, though for the most part it continues to hold approximately.
Otto Theodor Benfey's spiral periodic table (1964)
Iron, a metal
Sulfur, a nonmetal
Arsenic, an element often called a semi-metal or metalloid

The periodic table, also known as the periodic table of the (chemical) elements, is a tabular display of the chemical elements.

The smallest constituents of all normal matter are known as atoms.

The quark content of the neutron. The color assignment of individual quarks is arbitrary, but all three colors must be present. Forces between quarks are mediated by gluons.

Neutron

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Subatomic particle, symbol or, which has a neutral charge, and a mass slightly greater than that of a proton.

Subatomic particle, symbol or, which has a neutral charge, and a mass slightly greater than that of a proton.

The quark content of the neutron. The color assignment of individual quarks is arbitrary, but all three colors must be present. Forces between quarks are mediated by gluons.
Nuclear fission caused by absorption of a neutron by uranium-235. The heavy nuclide fragments into lighter components and additional neutrons.
Models depicting the nucleus and electron energy levels in hydrogen, helium, lithium, and neon atoms. In reality, the diameter of the nucleus is about 100,000 times smaller than the diameter of the atom.
A schematic of the nucleus of an atom indicating radiation, the emission of a fast electron from the nucleus (the accompanying antineutrino is omitted). In the Rutherford model for the nucleus, red spheres were protons with positive charge and blue spheres were protons tightly bound to an electron with no net charge. 
The inset shows beta decay of a free neutron as it is understood today; an electron and antineutrino are created in this process.
The Feynman diagram for beta decay of a neutron into a proton, electron, and electron antineutrino via an intermediate heavy W boson
The leading-order Feynman diagram for decay of a proton into a neutron, positron, and electron neutrino via an intermediate boson.
Institut Laue–Langevin (ILL) in Grenoble, France – a major neutron research facility.
Cold neutron source providing neutrons at about the temperature of liquid hydrogen
The fusion reaction rate increases rapidly with temperature until it maximizes and then gradually drops off. The D–T rate peaks at a lower temperature (about 70 keV, or 800 million kelvins) and at a higher value than other reactions commonly considered for fusion energy.
Transmutation flow in light water reactor, which is a thermal-spectrum reactor

Protons and neutrons constitute the nuclei of atoms.

Atoms of a chemical element that differ only in neutron number are called isotopes.

The quark content of a proton. The color assignment of individual quarks is arbitrary, but all three colors must be present. Forces between quarks are mediated by gluons.

Proton

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Stable subatomic particle, symbol, H+, or 1H+ with a positive electric charge of +1e elementary charge.

Stable subatomic particle, symbol, H+, or 1H+ with a positive electric charge of +1e elementary charge.

The quark content of a proton. The color assignment of individual quarks is arbitrary, but all three colors must be present. Forces between quarks are mediated by gluons.
Ernest Rutherford at the first Solvay Conference, 1911
Proton detected in an isopropanol cloud chamber
Protium, the most common isotope of hydrogen, consists of one proton and one electron (it has no neutrons). The term "hydrogen ion" implies that that H-atom has lost its one electron, causing only a proton to remain. Thus, in chemistry, the terms "proton" and "hydrogen ion" (for the protium isotope) are used synonymously

One or more protons are present in the nucleus of every atom.

Since each element has a unique number of protons, each element has its own unique atomic number, which determines the number of atomic electrons and consequently the chemical characteristics of the element.

Spectral lines of helium

Helium

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Spectral lines of helium
Sir William Ramsay, the discoverer of terrestrial helium
The cleveite sample from which Ramsay first purified helium
Historical marker, denoting a massive helium find near Dexter, Kansas
The helium atom. Depicted are the nucleus (pink) and the electron cloud distribution (black). The nucleus (upper right) in helium-4 is in reality spherically symmetric and closely resembles the electron cloud, although for more complicated nuclei this is not always the case.
Binding energy per nucleon of common isotopes. The binding energy per particle of helium-4 is significantly larger than all nearby nuclides.
Helium discharge tube shaped like the element's atomic symbol
Liquefied helium. This helium is not only liquid, but has been cooled to the point of superfluidity. The drop of liquid at the bottom of the glass represents helium spontaneously escaping from the container over the side, to empty out of the container. The energy to drive this process is supplied by the potential energy of the falling helium.
Unlike ordinary liquids, helium II will creep along surfaces in order to reach an equal level; after a short while, the levels in the two containers will equalize. The Rollin film also covers the interior of the larger container; if it were not sealed, the helium II would creep out and escape.
Structure of the helium hydride ion, HHe+
Structure of the suspected fluoroheliate anion, OHeF−
The largest single use of liquid helium is to cool the superconducting magnets in modern MRI scanners.
A dual chamber helium leak detection machine
Because of its low density and incombustibility, helium is the gas of choice to fill airships such as the Goodyear blimp.

Helium (from ἥλιος) is a chemical element with the symbol He and atomic number 2.

In the perspective of quantum mechanics, helium is the second simplest atom to model, following the hydrogen atom.

An explanation of the superscripts and subscripts seen in atomic number notation. Atomic number is the number of protons, and therefore also the total positive charge, in the atomic nucleus.

Atomic number

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An explanation of the superscripts and subscripts seen in atomic number notation. Atomic number is the number of protons, and therefore also the total positive charge, in the atomic nucleus.
The Rutherford–Bohr model of the hydrogen atom or a hydrogen-like ion (Z > 1). In this model it is an essential feature that the photon energy (or frequency) of the electromagnetic radiation emitted (shown) when an electron jumps from one orbital to another be proportional to the mathematical square of atomic charge (Z2). Experimental measurement by Henry Moseley of this radiation for many elements (from ) showed the results as predicted by Bohr. Both the concept of atomic number and the Bohr model were thereby given scientific credence.
Russian chemist Dmitri Mendeleev, creator of the periodic table.
Niels Bohr, creator of the Bohr model.
Henry Moseley in his lab.

The atomic number or nuclear charge number (symbol Z) of a chemical element is the charge number of an atomic nucleus.

For ordinary nuclei, this is equal to the proton number (np) or the number of protons found in the nucleus for every atom of that element.

A model of the atomic nucleus showing it as a compact bundle of the two types of nucleons: protons (red) and neutrons (blue). In this diagram, protons and neutrons look like little balls stuck together, but an actual nucleus (as understood by modern nuclear physics) cannot be explained like this, but only by using quantum mechanics. In a nucleus that occupies a certain energy level (for example, the ground state), each nucleon can be said to occupy a range of locations.

Atomic nucleus

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A model of the atomic nucleus showing it as a compact bundle of the two types of nucleons: protons (red) and neutrons (blue). In this diagram, protons and neutrons look like little balls stuck together, but an actual nucleus (as understood by modern nuclear physics) cannot be explained like this, but only by using quantum mechanics. In a nucleus that occupies a certain energy level (for example, the ground state), each nucleon can be said to occupy a range of locations.
A figurative depiction of the helium-4 atom with the electron cloud in shades of gray. In the nucleus, the two protons and two neutrons are depicted in red and blue. This depiction shows the particles as separate, whereas in an actual helium atom, the protons are superimposed in space and most likely found at the very center of the nucleus, and the same is true of the two neutrons. Thus, all four particles are most likely found in exactly the same space, at the central point. Classical images of separate particles fail to model known charge distributions in very small nuclei. A more accurate image is that the spatial distribution of nucleons in a helium nucleus is much closer to the helium electron cloud shown here, although on a far smaller scale, than to the fanciful nucleus image. Both the helium atom and its nucleus are spherically symmetric.

The atomic nucleus is the small, dense region consisting of protons and neutrons at the center of an atom, discovered in 1911 by Ernest Rutherford based on the 1909 Geiger–Marsden gold foil experiment.

Which chemical element an atom represents is determined by the number of protons in the nucleus; the neutral atom will have an equal number of electrons orbiting that nucleus.

Chemical compound

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A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) composed of atoms from more than one element held together by chemical bonds.

Helium was first detected in the Sun due to its characteristic spectral lines.

Noble gas

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Helium was first detected in the Sun due to its characteristic spectral lines.
This is a plot of ionization potential versus atomic number. The noble gases, which are labeled, have the largest ionization potential for each period.
Neon, like all noble gases, has a full valence shell. Noble gases have eight electrons in their outermost shell, except in the case of helium, which has two.
Structure of, one of the first noble gas compounds to be discovered
An endohedral fullerene compound containing a noble gas atom
Bonding in according to the 3-center-4-electron bond model
Liquid helium is used to cool superconducting magnets in modern MRI scanners
Goodyear Blimp
15,000-watt xenon short-arc lamp used in IMAX projectors

The noble gases (historically also the inert gases; sometimes referred to as aerogens ) make up a class of chemical elements with similar properties; under standard conditions, they are all odorless, colorless, monatomic gases with very low chemical reactivity.

The properties of the noble gases can be well explained by modern theories of atomic structure: Their outer shell of valence electrons is considered to be "full", giving them little tendency to participate in chemical reactions, and it has been possible to prepare only a few hundred noble gas compounds.

Theoretically predicted phase diagram of carbon, from 1989. Newer work indicates that the melting point of diamond (top-right curve) does not go above about 9000 K.

Carbon

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Theoretically predicted phase diagram of carbon, from 1989. Newer work indicates that the melting point of diamond (top-right curve) does not go above about 9000 K.
A large sample of glassy carbon
Some allotropes of carbon: a) diamond; b) graphite; c) lonsdaleite; d–f) fullerenes (C60, C540, C70); g) amorphous carbon; h) carbon nanotube
Comet C/2014 Q2 (Lovejoy) surrounded by glowing carbon vapor
Graphite ore, shown with a penny for scale
Raw diamond crystal
"Present day" (1990s) sea surface dissolved inorganic carbon concentration (from the GLODAP climatology)
Diagram of the carbon cycle. The black numbers indicate how much carbon is stored in various reservoirs, in billions tonnes ("GtC" stands for gigatonnes of carbon; figures are circa 2004). The purple numbers indicate how much carbon moves between reservoirs each year. The sediments, as defined in this diagram, do not include the ≈70 million GtC of carbonate rock and kerogen.
Structural formula of methane, the simplest possible organic compound.
Correlation between the carbon cycle and formation of organic compounds. In plants, carbon dioxide formed by carbon fixation can join with water in photosynthesis ( green ) to form organic compounds, which can be used and further converted by both plants and animals.
This anthracene derivative contains a carbon atom with 5 formal electron pairs around it.
Antoine Lavoisier in his youth
Carl Wilhelm Scheele
Diamond output in 2005
Pencil leads for mechanical pencils are made of graphite (often mixed with a clay or synthetic binder).
Sticks of vine and compressed charcoal
A cloth of woven carbon fibres
Silicon carbide single crystal
The C60 fullerene in crystalline form
Tungsten carbide endmills
Worker at carbon black plant in Sunray, Texas (photo by John Vachon, 1942)

Carbon (from carbo "coal") is a chemical element with the symbol C and atomic number 6.

It bonds readily with other small atoms, including other carbon atoms, and is capable of forming multiple stable covalent bonds with suitable multivalent atoms.