Exam Revision Q&A
Ask a question to be in with the chance of winning a £50 Amazon voucher. Answer a question to be in with the chance of winning a £100 Amazon voucher!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?
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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