Question

The elements of the third period of the periodic table are given below:
Group I II III IV V VI VII
Na Mg Al Si P S Cl
(a) Which atom is bigger - Na or Mg ? Why ?
(b) Identify the most
(i) Metallic and
(ii) Non-metallic element in period 3.

Answer 1

(a) Na atom is bigger in size because as we move from Na to Cl, the atomic number goes on increasing and the nuclear charge also increases. It pulls/ attract the valence electrons at the centre more efficiently and thus the atomic size decreases.
(b) (i) Most metallic - $Na$
(ii) Most non-metallic - $Cl$