Proton
Definition
The positively charged particle in an atom's nucleus. The number of protons decides which element an atom is.
Symbol: · Unit: 1.602 x 10^-19 C
Technical definition
A proton is a positively charged subatomic particle (charge +1e, mass about 1.0073 u) located in the atomic nucleus. The proton count, called the atomic number, defines the element's identity, and it changes only in nuclear reactions.
Example
Every hydrogen atom has 1 proton and every carbon atom has 6 protons. Add a proton to carbon and it becomes nitrogen.
Common confusion
Protons are not the particles that move in chemical reactions, electrons are. Protons stay locked in the nucleus during ordinary chemistry.