For example, oxygen has eight protons, silicon has fourteen. Protons have a positive charge that is balanced by the negatively charged electrons. Neutrons are neutral, they have no charge. Different shells hold different numbers of electrons. The two innermost shells hold 2 and 8 electrons respectively.
Outer shells can hold more electrons but are considered stable when they contain eight electrons.
The number of electrons should ideally equal the number of protons. However, atoms may loose or gain electrons to reach a configuration with a stable outer shell. This results in the formation of a negatively or positively charged atom known as an ion . Anions may form where an atom with a nearly full outer shell gains electrons. The silicon atom's fourteen protons are balanced with an equal number of electrons.