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Here [Ne] refers to the core electrons which are the same as for the element neon (Ne), the last noble gas before phosphorus in the periodic table. The valence electrons (here 3s 2 3p 3) are written explicitly for all atoms. Electron configurations of elements beyond hassium (element 108) have never been measured; predictions are used below.
Configurations of elements 109 and above are not available. Predictions from reliable sources have been used for these elements. Grayed out electron numbers indicate subshells filled to their maximum. Bracketed noble gas symbols on the left represent inner configurations that are the same in each period. Written out, these are: He, 2, helium : 1s 2
For example, chlorine (element 17), with electron configuration 1s 2 2s 2 2p 6 3s 2 3p 5, has 17 protons and 10 inner shell electrons (2 in the first shell, and 8 in the second) so: Core charge = 17 − 10 = +7. A core charge is the net charge of a nucleus, considering the completed shells of electrons to act as a 'shield.'
The electron configuration can be visualized as the core electrons, equivalent to the noble gas of the preceding period, and the valence electrons: each element in a period differs only by the last few subshells. Phosphorus, for instance, is in the third period.
Starting from the third element, lithium, the first shell is full, so its third electron occupies a 2s orbital, giving a 1s 2 2s 1 configuration. The 2s electron is lithium's only valence electron, as the 1s subshell is now too tightly bound to the nucleus to participate in chemical bonding to other atoms: such a shell is called a " core shell ".
Similar to a core electron, a valence electron has the ability to absorb or release energy in the form of a photon. An energy gain can trigger the electron to move (jump) to an outer shell; this is known as atomic excitation. Or the electron can even break free from its associated atom's shell; this is ionization to form a positive ion. When an ...
Template: Periodic table (electron configuration) 5 languages. ... Electron configurations of the chemical elements (neutral gaseous atoms in the ground state; ...
The effective nuclear charge experienced by an electron is also called the core charge. It is possible to determine the strength of the nuclear charge by the oxidation number of the atom. Most of the physical and chemical properties of the elements can be explained on the basis of electronic configuration.