# What does a radical mean here?

I'm really confused as none of the definitions of radical on the internet compare to this.

This is from my college textbook of Applied Chemistry-

Every inorganic compound is made up of two electrically charged parts called radicals. One part has positive charge and is called basic radical, while the other part has negative charge and is called acid radical. Hence,

An atom or a group of atoms which forms a part of an inorganic compound is called a radical.

For example :

1. Sodium Chloride is made up of two parts:

The two radicals combine to form sodium chloride molecule.

1. Copper sulphate is made up of two parts:

The two radicals combine to form copper sulphate molecule.

It should be noted that a radical cannot exist independently.

This definitely doesn't mean the same as free radicals. I don't think it means "functional group" because how can sodium be a functional group?!. Functional groups are in organic chemistry, right?

Can someone explain what the term "radical" means here?

A molecular entity such as $\ce{.CH3}$, $\ce{.SnH3}$, $\ce{Cl.}$ possessing an unpaired electron.