Question

1. Write the electronic configuration of element X, given by its symbol as under: \[\ce{^40_20 X}\]
2. Determine its position in the modem periodic table.
3. What is the nature of its oxide?
4. Name one other element of its group.

Answer 1

(i) The atomic number of the given element X is 20. The electronic configuration will be 2, 8, 8, 2.

(ii) The element corresponding to the atomic number 20 is calcium.
Calcium belongs to 4th period as it contains 4 shells and 2^nd group as it has two valence electrons.

(iii) The valence of both calcium and oxygen is 2. Therefore, the formula of their oxide is CaO. Being a metallic oxide, CaO is basic in nature.

(iv) Magnesium (Mg).