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IGCSE Physics, Cambridge 0625, Malaysia

Proton

Symbol: p

A positively charged subatomic particle found in the nucleus with a relative charge of +1 and a relative mass of 1.

Protons carry a positive charge of +1.6×1019+1.6 \times 10^{-19} C and have a relative mass of 1.

The number of protons (proton number, ZZ) defines which element an atom is. All atoms of a given element have the same number of protons.

In a neutral atom, the number of protons equals the number of electrons. Losing or gaining electrons creates ions, but the number of protons does not change in chemical reactions.

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