An atom consists of a small positively charged nucleus surrounded by an equal number of negatively charged electrons.
In a stable, neutral atom there are the same amounts of positive and negative charges.
All electrostatic effects are due to the movement of electrons.
The law of electric charge states that: like charges repel, unlike charges attract.
When a polythene rod is rubbed with a duster, electrons are transferred from the acetate to the duster, leaving the acetate rod positively charged.
In general an object has:
-a negative charge due to an excess of electrons
-a positive charge due to a lack of electrons
Atoms or molecules that have become charged are ions.