Question

Which are the most reactive metallic and non metallic elements
Which group will react with oxygen to give
A, covalent compounds with formula XO2
B, eletrovalent compounds with formula X2O

Answer 1

Francium is the most reactive metal. Fluorine has the highest electronegativity and the smallest atomic radius therefore it gains valence electrons the most easily. The most reactive nonmetals are those that can most easily gain valence electrons. Fluorine is the most reactive nonmetal.

A. $X^{+4} + 2O^{2-} → XO_2$

X has a valency of +4.

Hence, X belongs to group 4.

B. $2X^{+1} +O^{2−} → X_2O$

X has a valency of +1.

Hence, X belongs to group 1.