Revise Nuclide Notation – S3 Chemistry Consolidation

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Nuclide notation is a shorthand method of showing information about atoms. Numbers are arranged around the outside of the atom’s symbol. The information provide by nuclide notation is detailed in the diagram opposite. This diagram shows the nuclide notation for a sodium ion (which has a 1+ charge).

Number of Protons	This is the same as the atomic number – so in the example is 11
Number of electrons	For atoms, this will be the same as the atomic number.
	However ions are different, in that they have a charge. If the ion is positively charged, it means it has lost electrons(s). Consequently, the number of electrons will be calculated by subtracting the charge from the number of protons (atomic number – which never changes).
	In this example, the number electrons equals 10.
	If the ion is negatively charged, it means the atom has gained extra electrons. In this case the number of electrons will calculated by adding the charge to the number of protons (atomic number).
Number of Neutrons	The mass of an atom is given by the number of neutrons (mass – 1 amu) plus the number of protons (mass – 1 amu).
	Consequently, the number of neutrons can be calculated by subtracting the atomic number (number of protons) from the mass number.
	In this example, the number of neutrons equals 12.

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