# Thallium valence electrons

Thallium has 3 valence electrons.

Contents

## Methods

We can write the valence electrons of thallium using two different methods:

#1 Using periodic table
#2 Using electron configuration

Let’s break down each method in detail.

### Using periodic table

Get the periodic table having the chemical elements marked on it as mentioned above.

Now mark the location of thallium on the periodic table.

Next, mark the group number of thallium on the periodic table.

The valence electrons of each main-group element can be determined by the column in which it is located.

(i.e., all group 1 elements have 1 valence electron, all group 2 elements have 2 valence electrons, skip the transition metals… then, all group 13 elements have 3 valence electrons, all group 14 elements have 4 valence electrons, and so on up to group 18 elements)

Since thallium is in group 13, it has 3 valence electrons.

### Using electron configuration

• First, write electron configuration of thallium

The electron configuration of thallium is [Xe] 6s2 4f14 5d10 6p1.

• Second, find highest energy level in electron configuration

In the above electron configuration, the highest energy level (6) is marked with green color.

• Finally, count electrons of that energy level

The 6th energy level contains 6s and 6p subshells. There are 2 electrons in the 6s subshell and 1 electron in the 6p subshell. So thallium has a total of 2 + 1 = 3 valence electrons.