Classification Of Elements And Periodicity In Properties Ques 8
8. Identify the wrong statement in the following:
[2012]
(a) Amongst isoelectronic species, smaller the positive charge on the cation, smaller is the ionic radius.
(b) Amongst isoelectronic species, greater the negative charge on the anion, larger is the ionic radius.
(c) Atomic radius of the elements increases as one moves down the first group of the periodic table.
(d) Atomic radius of the elements decreases as one moves across from left to right in the $2^{\text{nd }}$ period of the periodic table.
Show Answer
Answer : a
Hints & Solutions
(a) Statement (a) is wrong. Among isoelectronic species, smaller the positive charge on the cation, larger is the ionic radius (not smaller). For example, among Na+, Mg2+ and Al3+ (all isoelectronic with 10 electrons), Na+ has the smallest positive charge but the largest ionic radius because the nuclear charge pulling on the same number of electrons is least. As positive charge increases, the nuclear charge acts on fewer electrons and pulls them closer, decreasing the radius.
BETA
