How can I calculate the number of neutrons in the nucleus of an atom?

1 Answer
Callum S.
Oct 8, 2014

To calculate the number of neutrons in the nucleus of an atom is simple. You take the atomic, or proton number of the element, and you subtract it from the element's mass number.

For example, take the isotope of copper, Cu-63. It contains 29 protons and has a mass number of 63, as suggested in the name. In order to calculate the number of neutrons, you must take its mass number (63) away from its atomic number (29), which leaves you with 46. Therefore, Cu-63 contains 29 protons, and 46 neutrons.

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