Protons

**Definition:** Stable elementary particles having the smallest known positive charge, found in the nuclei of all elements. The proton mass is less than that of a neutron. A proton is the nucleus of the light hydrogen atom, i.e., the hydrogen ion.

**Tree numbers:** - D01.248.497.300.459.700 - D01.268.406.750 - D01.362.340.750 - G01.249.660.500

**Synonyms:** - Hydrogen Ions