QQuestion
Give reasons why:
(a) Hydrochloric acid cannot form an acid salt.
(b) Electronegativity increases across a period.
✓Answer
(a) Hydrochloric acid (HCl) is a monobasic acid, i.e., it has only one replaceable hydrogen ion per molecule. Acid salts are formed by the partial replacement of replaceable hydrogen ions of an acid by a metal, which requires the acid to be at least dibasic (with two or more replaceable H+). Since HCl has only one replaceable hydrogen, it can only form normal salts and not acid salts.
(b) On moving across a period from left to right, the nuclear charge increases while the number of shells (energy levels) remains the same. As a result, the atomic radius decreases and the effective pull of the nucleus on the bonding electrons increases. Hence, the tendency of an atom to attract the shared pair of electrons (electronegativity) increases across a period.
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