Question

Show diagrammatically the electron distributions in a sodium atom and a sodium ion and also give their atomic number.

Answer 1

Sodium atom:

• The atomic number of sodium is 11 and the electronic configuration of sodium is,
• Na (Z = 11) = $1{\mathrm{s}}^2,2{\mathrm{s}}^2,2{\mathrm{p}}^6,3{\mathrm{s}}^1.$

The distribution of electrons in the sodium atom is as follows:

• In the first orbit or K-shell = 2 electrons
• In the second orbit or L-shell = 8 electrons
• In the third orbit or M-shell = 1 electron
• Or, we can write the distribution of electrons in a sodium atom as 2, 8, 1.

Sodium-ion:

• Na⁺ ion is formed from sodium atom by loss of an electron (present in the outermost shell).
• Hence, the electronic configuration is 2, 8(K, L). However, the number of protons and neutrons remains the same.