Proton

what is a proton?

A proton is a type of subatomic particle found in the nucleus of every atom. It carries a single positive electric charge (+1e) and is one of the three main particles that make up an atom, alongside neutrons and electrons.

The number of protons in an atom determines its atomic number and ultimately defines the element itself.

basic properties of protons

• symbol: p⁺
• charge: +1
• mass: approximately 1 atomic mass unit (amu) or 1.6726 × 10⁻²⁷ kg
• location: inside the nucleus of the atom
• stability: stable in all known cases

discovery

Protons were discovered by British physicist ernest rutherford in 1917 during his famous gold foil experiment. He observed that hydrogen nuclei were emitted during nuclear reactions and named these positively charged particles "protons."

role of protons in the atom

• identity of an element: the number of protons equals the element’s atomic number.
• charge balance: in a neutral atom, the number of protons equals the number of electrons.
• mass of the atom: protons contribute significantly to the atomic mass along with neutrons.
• chemical behavior: protons influence the atom’s interaction with other atoms, particularly through their effect on electron configuration.

protons vs neutrons vs electrons

comparison of subatomic particles

particle	charge	mass (approx)	location
proton	+1	1 amu	nucleus
neutron	0	1 amu	nucleus
electron	−1	1/1836 amu	electron cloud/orbitals

protons and isotopes

While all atoms of a given element have the same number of protons, they can have different numbers of neutrons. These variants are called isotopes.

Example:

• carbon-12 and carbon-14 both have 6 protons, but 6 and 8 neutrons respectively.

protons in nuclear reactions

Protons play a key role in:

• nuclear fusion – hydrogen nuclei (protons) fuse to form helium in stars.
• nuclear fission – changes in the number of protons during radioactive decay can transform one element into another.
• ionization – loss or gain of electrons doesn't change the number of protons, but alters the atom's net charge.

importance of protons

• fundamental to the identity of matter
• determine an element’s position in the periodic table
• drive nuclear reactions in stars
• used in proton therapy for cancer treatment

see also

• atomic number
• nucleus
• neutrons
• electrons
• periodic table
• ernest rutherford

references and further reading

• Khan Academy – Atomic structure
• Royal Society of Chemistry
• NCERT Chemistry Textbooks
• The Physics Hypertextbook

disclaimer

This article is intended for educational and academic purposes only. It is designed to support science learning in school-level MediaWiki environments. For in-depth scientific study, consult peer-reviewed sources and curriculum-based textbooks.