Electrons are outside the nucleus . Each electron has a single negative electric charge. Electricity is the flow of electrons in wires. This gives atoms an overall charge of zero. Electronic Structure Atoms have shells available for electrons.
Electrons fill the innermost shells first.
This gives them the most stable electronic structure. Atoms with only one or two electrons in their outer shells lose them easily. This is why groups 1 and 2 are the most strongly metallic elements. Group seven elements have one electron less than the noble gases. The tutorial uses animations to relate electronic structure to ionic bonding.