Question

Calcium is an element with atomic number 20. Stating reason
answer each of the following questions :
(i) Is calcium a metal or non-metal?
(ii) Will its atomic radius be larger or smaller than that of potassium
with atomic number 19 ?
(iii) Write the formula of its oxide.

Answer 1

ANSWER...

1-ITS A METAL BECAUSE VALENCE ELECTRONS ARE 2 ....

2-IT WILL BE SMALLER THAN K BECAUSE ATOMIC SIZE DECREASES ACROSS A PERIOD.

3-ITS OXIDE IS CALCIUM OXIDE CaO .

hope it helps

Answer 2

(i)Calcium is a metal since it's located on the left side of the periodic table and it loses electrons easily. Mainly, it has metallic properties

(ii)It's atomic radius will be smaller than that  of potassium as calcium has one more proton than potassium but both of them have the same number of shells so the net positive charge increases but the shells are in the same number so the atomic radius decreases. Also because calcium is located closer to the right than potassium in the periodic table.

(iii)CaO    the valency of calcium is -2 and valency of oxygen is+2  therefore oxygen loses two electrons and calcium gains those two electrons to get stable and they form an ionic bond.