Question

Which pair a atomic numbers represents elements in the same group.

a) 11, 19 b) 6, 12

c) 4, 16 d) 8, 17

Answer 1

your answer is (a) 11 and 19
as they have same number of valence electrons

Answer 2

The (a) 11, 19 represents elements in the same group.

• The elements of the same groups have the same valencies.
• The electronic configuration of 11 is 2,8,1 and that of 19 is 2,8,8,1, so both the atoms have +1 valency.
• The +1 valency of both the atoms implies that they can donate one outermost electron to acquire stability.
• The elements of the same groups have the same electronic configurations.
• The number of shells increases as we move down the same group.

Hence, (a) 11, 19 represent elements in the same group.