Question

Which metal in Period 5 is very reactive and has two valence electrons in each atom?

Answer 1

The answer is Strontium(Sr). The reactive increase from right to left. And this element has two valence electrons. So Rb is not correct. Then the very reactive metal is Sr.

Answer 2

Answer: The correct answer is Strontium.

Explanation:

Reactivity of an element is defined as the tendency to loose or gain electrons. Reactivity decreases as we move from left to right in a period and it increases as we move from up to down in a group.

A metal which belongs to Period 5 and has 2 valance electrons is Strontium. This element belongs to Group 2.

The electronic configuration of strontium (Sr) = $[Kr]5s^2$

Hence, the correct answer is Strontium.