The melting points and boiling points of some ionic compounds are given below : Compound | Melting Point (K)…
The melting points and boiling points of some ionic compounds are given below :
Compound | Melting Point (K) | Boiling Point (K)
NaCl | 1074 | 1686
LiCl | 887 | 1600
CaCl2 | 1045 | 1900
CaO | 2850 | 3120
MgCl2 | 981 | 1685
These compounds are termed ionic because they are formed by the transfer of electrons from a metal to a non-metal. The electron transfer in such compounds is controlled by the electronic configuration of the elements involved. Every element tends to attain a completely filled valence shell of its nearest noble gas or a stable octet.
(i) Show the electron transfer in the formation of magnesium chloride. [1]
(ii) List two properties of ionic compounds other than their high melting and boiling points. [1]
(iii) (A) While forming an ionic compound say sodium chloride how does sodium atom attain its stable configuration ? [2]
Solution
(i) Mg + 2 Cl → (Mg2+) [Cl]2- (electron dot / Lewis structure showing formation of ionic bond between Mg and 2 Cl atoms)
(ii) They are hard solids
They are soluble in water
They conduct electricity in aqueous solution or molten state
[Any two]
(iii) (A) Sodium atom has one electron in its outermost shell
It attains its nearest noble gas configuration by losing this electron forming Na+ ion / Na → Na+ + e-
2,8,1 2,8
stable