Question

Which of the following elemental sequence represents an increase in atomic size?

Answer 1

Answer:

A) B, C, Na, AI, K

Explanation:

This is because from the periodic table, the atomic size of each element increases as we go along the periodic table.

The atomic numbers of the elements are B = 5, C = 6 , Na = 11, Al = 13 and K = 19.

The electronic configuration of each element is given as follows

B = 2, 3; C = 2, 4; Na = 2, 8, 1; Al = 2, 8, 3 and K = 2, 8, 8, 1

Since the atomic numbers increase from left to right as we go along the periodic table, their atomic sizes also increase.

Also, from their electronic configurations, Boron (B)and Carbon (C) only have electrons on the K and L shell. Sodium (Na) and Aluminium (Al) have electrons on the K, L and M shells while Potassium (K) has electrons on the K, L, M and N shells.

So, the larger the electronic configuration, the larger the atomic radius and thus atomic size.

So, they increase in the order B, C, Na, Al, K