Question

Write down the electronic configuration of the first three elements of group 1. How many valence electrons are present in each one of these elements?

Answer 1

Step-1: Introduction

The elements in periodic table are placed in periods and groups. Periods are horizontal rows that has increasing atomic numbers. Groups are vertical columns. The groups have similar chemical properties. There are 7 periods and 18 groups in periodic table.

The elemental classification in the periodic table long form is electronic configuration.

The electrons in the outermost shell of the element are valence electrons. It is same for a particular group.

Step-2: Group 1 elements

Group 1 elements include Lithium ($\mathrm{Li}$), Sodium ($\mathrm{Na}$), Potassium ($\mathrm{K}$), Rubidium ($\mathrm{Rb}$), Cesium ($\mathrm{Cs}$) and Francium ($\mathrm{Fr}$).

Lithium, Sodium and Potassium are the first three elements of group 1.

Configuration of group 1 elements

Electronic configuration of Lithium is (2,1).

Electronic configuration of Sodium is (2,8,1).

Electronic configuration of Potassium is (2,8,8,1).

Step-3:

All the three elements have same valence electrons count. The valence electron count is 1.

Therefore, the valence electron count is 1 in each one of these elements.