What is the structure of an atom?

Atoms are really tiny particles that make up all substances in the universe. An element is made of one type of atom. An atom has a small central nucleus made up of smaller sub-atomic particles called protons and neutrons. The nucleus is surrounded by even smaller sub-atomic particles called electrons. Atoms always have the same number of protons and electrons. Protons are positive (think - they both begin with the letter P!), electrons are negative and Neutrons are Neutral (Think - they both begin with the letter N!). Protons and electrons have an electrical charge. Both have the same size of electrical charge and because they are equal in number the overall charge of an atoms is zero.