Eg-1. Formation of sodium chloride [NaCl]:
Sodium chloride is formed from the elements sodium and chlorine. It can be explained as follows:
Na(s)+ 1/2 Cl2(g) → NaCl(s)
Cation formation
When sodium (Na) atom loses one electron to get octet electron configuration it forms a cation (Na+) and gets electron configuration that of Neon (Ne) atom.
11Na(g) → 11Na+(g) + e-
E.C. 2, 8, 1 2, 8
or [Ne] 3s1 [Ne]Anion formation
Chlorine has shortage of one electron to get octet in its valence shell. So it gains the electron from Na atom to form anion and gets electron configuration as that of argon (Ar).
17Cl(g) + e- → Cl-(g)Electronic Configuration 2,8,7 2,8,8
or [Ne]3s23p5 [Ne]3s23p6 or [Ar]
Formation of the compound NaCl from its ions:
Transfer of electrons between ‘Na’ and ‘Cl’ atoms, results in the formation of ‘Na+ and ‘Cl’- ions.These oppositely charged ions get attracted towards each other due to electrostatic forces and form the compound sodium chloride (NaCl).
Na+(g) + Cl-(g) → Na+Cl- (s)orNaCl
Eg-2. Formation of magnesium chloride (MgCl2):
Magnesium chloride is formed from the elements magnesium and chlorine.The bond formation MgCl2 in brief using chemical equationis as follows:
Mg(s) + Cl2(g) → MgCl2(s)Cation formation
12Mg(g) →12Mg2+ (g) + 2e-Electronic configuration 2,8,2 2,8
or [Ne]3s2 [Ne]
Anion formation
2Cl(g) + 2e- → 2Cl- (g)Electronic configuration2,8,7 2,8,8
or [Ne]3s23p5 [Ne]3s23p6or [Ar]