Question

What element has 81 protons in the nuclei of its atoms?

Answer 1

The element that has 81 protons in the nuclei of its atoms is Thallium.

The number of protons in the nuclei of its atoms, is the atomic number of the element.

So, according to he periodic table, atomic mass of Thallium is 204.383 atomic mass unit.

Number of protons and electrons is 81 and number of neutrons is 123 in Thallium.

Answer 2

$\textbf{Thallium}$ is that atom having 81 protons in its nuclei.

This element comes in period number 6 and group 13.

This element has valency of +1 and +3.

Its atomic weight is 204.3

It is denoted by TI.