Question

An element belongs to Group $17$ and the third period of the periodic table. Write the following:

Its valency.

Answer 1

Valency:

1. Valency is known as the number of electrons required by an element to be gained or lost to attain the noble gas configuration.
2. Valency gives the combining capacity of an element

Chlorine $\left(\mathrm{Cl}\right)$:

1. The element that belongs to group $17$ and the third period is Chlorine $\left(\mathrm{Cl}\right)$.
2. The electronic configuration of chlorine is $\mathrm{Cl}\to 2,8,7$
3. The electrons are filled in three shells, therefore Chlorine is in the third period and has 7 valence electrons.

Therefore, the element is Chlorine and it has valency $7$