A report on Chemical element

The chemical elements ordered in the periodic table

$Estimated distribution of dark matter and dark energy in the universe. Only the fraction of the mass and energy in the universe labeled "atoms" is composed of chemical elements.$

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

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.

Mendeleev's 1869 periodic table: An experiment on a system of elements. Based on their atomic weights and chemical similarities.

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

- Chemical element

148 related topics with Alpha

Periodic table

42 links

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.)

Graph of first ionisation energies of the elements in electronvolts (predictions used for elements 105–118)

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

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)

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.

Atom

29 links

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.

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.

The binding energy needed for a nucleon to escape the nucleus, for various isotopes

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.

This diagram shows the half-life (T½) of various isotopes with Z protons and N neutrons.

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.

The three naturally-occurring isotopes of hydrogen. The fact that each isotope has one proton makes them all variants of hydrogen: the identity of the isotope is given by the number of protons and neutrons. From left to right, the isotopes are protium (1H) with zero neutrons, deuterium (2H) with one neutron, and tritium (3H) with two neutrons.

Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numbers) due to different numbers of neutrons in their nuclei.