Atomic Structure
Every atom is made of a nucleusconsisting of protons and neutrons. The nucleus is surrounded by electrons. Protons and electrons are oppositely charged. Neutrons have no charge. This means the nucleus of an atom is always positively charged.
An atom has a neutral overall charge because it has the same number of electrons as protons.
Protons and neutrons have the same mass. Electrons have such a small mass that this can usually be taken as zero.
