To understand something of electricity it is necessary to understand something about the structure of materials, in particular atomic structure.
All matter is composed of very small particles called atoms .
The three sub-atomic particles that concern us are the proton, the neutron and the electron. The nucleus can be thought of in terms of the core of the atom. It is in this extra-nuclear region that is occupied by the electrons. These figures for mass are obviously not very convenient and so chemists have assigned different units to record atomic masses. We need not worry too much about where the electrons are, we can simply imagine they form a cloud around the nucleus.