Proton: definition in chemistry
Proton: A positively charged subatomic particle (+1) found in the nucleus of every atom. The number of protons is the atomic number and decides which element an atom is.
A proton has a mass of about 1 atomic mass unit, roughly 1,836 times the mass of an electron. Its charge exactly balances that of one electron, so a neutral atom has equal numbers of protons and electrons. A hydrogen ion (H⁺) is a hydrogen atom that has lost its only electron, leaving a bare proton, which is why acids are often called proton donors.
Examples
- Hydrogen has 1 proton, carbon has 6 and gold has 79
- Adding a proton to a carbon nucleus would turn it into nitrogen
- The H⁺ ions released by acids are protons
- A proton is about 1,836 times heavier than an electron
On the periodic table
Elements are arranged on the table in order of their number of protons, so each step to the next element adds one proton.