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Protons and neurons...
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Protons and neurons not equal (periodic table)


Topic starter

I have seen in some practice questions i have tried photon and neutron numbers varying with that listed on the periodic table. Why does this happen?

1 Answer

Hi Alf 

The number of neutrons in different isotopes of the same atom can vary which would explain the varying mass numbers you are seeing. 

mass number = number of protons + number of neutrons

Isotopes are atoms which have the same atomic number (number of protons) but a different mass number due to there being a different number of neutrons in each isotope of the element.

There is no rule stating that the number protons and neutrons in an atomic element must be equal. I am not sure what you mean by proton number varying with that listed. Atoms of the same element have the same number of protons, so this could be a mistake in the practice questions.


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