Example of a sodium electron shell model

An electron shell, also known as a main energy level, is a group of atomic orbitals with the same value of the principal quantum number n. Electron shells are made up of one or more electron subshells, or sublevels, which have two or more orbitals with the same angular momentum quantum number l. Electron shells make up the electron configuration of an atom. It can be shown that the number of electrons that can reside in a shell is equal to 2n^{2 [1]}. Image File history File links Electron_shell_011_Sodium. ... Image File history File links Electron_shell_011_Sodium. ... In chemistry, an atomic orbital is the region in which an electron may be found around a single atom. ... In atomic physics, the principal quantum number symbolized as n is the first quantum number of an atomic orbital. ... Electron atomic and molecular orbitals In atomic physics and quantum chemistry, the electron configuration is the arrangement of electrons in an atom, molecule, or other physical structure (, a crystal). ... Properties For other meanings of Atom, see Atom (disambiguation). ... For other uses, see Electron (disambiguation). ...

History

The existence of electron shells was first observed experimentally in Charles Barkla's and Henry Moseley's X-ray absorption studies. Barkla labelled them with the letters K, L, M, etc. (The origin of this terminology was alphabetic. K for hypothetical spectral lines that were never discovered.) These letters were later found to correspond to the n-values 1, 2, 3, etc. They are used in the spectroscopic Siegbahn notation. Charles Glover Barkla (June 7, 1877 – October 23, 1944) was an English physicist. ... This article is about the physicist; for the naturalist see Henry Nottidge Moseley Henry Moseley at work. ... In the NATO phonetic alphabet, X-ray represents the letter X. An X-ray picture (radiograph) taken by Röntgen An X-ray is a form of electromagnetic radiation with a wavelength approximately in the range of 5 pm to 10 nanometers (corresponding to frequencies in the range 30 PHz... The Siegbahn notation is used to name the spectral lines that are characteristic to elements. ...

The name for electron shells originates from the Bohr model, in which groups of electrons were believed to orbit the nucleus at certain distances, so that their orbits formed "shells" around the nucleus. The Bohr model of the hydrogen atom () or a hydrogen-like ion (), where the negatively charged electron confined to an atomic shell encircles a small positively charged atomic nucleus, and an electron jump between orbits is accompanied by an emitted or absorbed amount of electromagnetic energy . ...

Valence shell

The valence shell is the outermost shell of an atom in its uncombined state, which contains the electrons most likely to account for the nature of any reactions involving the atom and of the bonding interactions it has with other atoms. Care must be taken to note that the outermost shell of an ion is not commonly termed valence shell. Electrons in the valence shell are referred to as valence electrons. The physical chemist Gilbert Lewis was responsible for much of the early development of the theory of the participation of valence shell electrons in chemical bonding. Linus Pauling later generalized and extended the theory while applying insights from quantum mechanics. Properties For other meanings of Atom, see Atom (disambiguation). ... For other uses, see Electron (disambiguation). ... For other uses, see Chemical reaction (disambiguation). ... A chemical bond is the physical process responsible for the attractive interactions between atoms and molecules, and that which confers stability to diatomic and polyatomic chemical compounds. ... In chemistry, valence electrons are the electrons contained in the valence shell of an atom, and which are likely to participate in a chemical reaction through bonding with other atoms or molecules. ... Physical chemistry is the study of the physical basis of chemical systems and processes. ... Lewis in the Berkeley Lab Gilbert Newton Lewis (October 23, 1875-March 23, 1946) was a famous physical chemist. ... Linus Carl Pauling (February 28, 1901 – August 19, 1994) was an American quantum chemist and biochemist. ... For a less technical and generally accessible introduction to the topic, see Introduction to quantum mechanics. ...

In a noble gas, an atom tends to have 8 electrons in its outer shell (except helium, which is only able to fill its shell with 2 electrons). This serves as the model for the octet rule which is mostly applicable to main group elements of the second and third periods. In terms of atomic orbitals, the electrons in the valence shell are distributed 2 in the single s orbital and 2 each in the three p orbitals. This article is about the chemical series. ... The bonding in carbon dioxide The octet rule is a simple chemical rule of thumb that states that atoms tend to combine in such a way that they each have eight electrons in their valence shells, similar to the electronic configuration of a noble gas. ... The periodic table of the chemical elements A chemical element, or element, is a type of atom that is defined by its atomic number; that is, by the number of protons in its nucleus. ... The Periodic Table redirects here. ... An atomic orbital is the description of the behavior of an electron in an atom according to quantum mechanics. ...

For coordination complexes containing transition metals, the valence shell consists of electrons in these s and p orbitals, as well as up to 10 additional electrons, distributed as 2 into each of 5 d orbitals, to make a total of 18 electrons in a complete valence shell for such a compound. This is referred to as the eighteen electron rule. Synthesis of copper(II)-tetraphenylporphine, a metal complex, from tetraphenylporphine and copper(II) acetate monohydrate. ... In chemistry, the term transition metal (sometimes also called a transition element) has two possible meanings: It commonly refers to any element in the d-block of the periodic table, including zinc, cadmium and mercury. ...

Each shell can hold 2, 8, 18, or 32 electrons, or 2x² electrons in each subshell. The notation 's', 'p', 'd', and 'f' originate from a now-discredited system of categorizing spectral lines as "sharp", "principal", "diffuse", or "fundamental", based on their observed fine structure. When the first four types of orbitals were described, they were associated with these spectral line types, but there were no other names. The designations 'g', 'h', and so on, were derived by following alphabetical order. A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from an excess or deficiency of photons in a narrow frequency range, compared with the nearby frequencies. ... In atomic physics, the fine structure describes the splitting of the spectral lines of atoms. ...

See also

• Atomic orbital
• Electron configuration
• Molecular orbital
• Open shell / closed shell

In chemistry, an atomic orbital is the region in which an electron may be found around a single atom. ... Electron atomic and molecular orbitals In atomic physics and quantum chemistry, the electron configuration is the arrangement of electrons in an atom, molecule, or other physical structure (, a crystal). ... In chemistry, a molecular orbital is a region in which an electron may be found in a molecule. ... In the context of atomic orbitals, an open shell is a valence shell which is not completely filled with electrons or which has not given all of its valence electrons through chemical bonds with other atoms or molecules during a chemical reaction. ...

References