Answer:
Electronic configuration, also called electronic structure, the arrangement of electrons in energy levels around an atomic nucleus. In terms of a more refined, quantum-mechanical model, the K–Q shells are subdivided into a set of orbitals (see orbital), each of which can be occupied by no more than a pair of electrons.
Explanation:
Electron Configuration with Examples
Electrons are not placed at fixed positions in atoms, but we can predict approximate positions of them. These positions are called energy levels or shells of atoms.
Lowest energy level is 1 and it is denoted with integer n=1, 2, 3, 4, 5, 6... or letters starting from K, L, N to Q. An atom can have maximum 7 energy levels and electrons can change their levels according to their energies.
Each energy level has different number of electrons. For example, we can find number of electrons in four energy level with following formula; 2n2.
1st energy level has;
2n2=2.12=2 electrons
2nd energy level has;
2n2=2.22=8 electrons
3rd energy level has;
2n2=2.32=18 electrons
Electrons are located energy levels starting from the first energy levels. If one of the energy level is full, then electrons are placed following energy level.
Example: Helium 2
1s²
Where;
1 is the principal quantum number or energy level (shell)
s is the sub-level or sub shell (Capacity of s sub shell is 2 electron)
2 shows the number of electrons in the s sub shell
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Example: Chlorine 17
1s²2s²2p⁶3s²3p⁵
Coefficients 1, 2, 2, 3, and 3 are energy levels of Cl. As you can see "p" sub shell can have maximum 6 electrons.
Superscripts 2, 2, 6, 2 and 5 are electrons in the sub shells "s" and "p".
Example: Bromine 35
1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p⁵
As you can see "d" sub shell can have maximum 10 electrons.
Example: Tantalum 73
1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p⁶5s²4d¹⁰5p⁶6s²4f¹⁴5d³
As you can see "f" sub shell can have maximum 14 electrons.
