Question

Determine the atomic number and mass number of an isotope that has 56

electrons and 82 neutrons.

Answer 1

Atomic number: 56

Mass number: 138

Step-by-step explanation:

Isotopes are atoms which have different numbers of neutrons. This means that although the number of neutrons is different, the number of protons and electrons are the same as the original element. Since atoms always have the same number of protons as electrons (not including ions etc.), this isotope will have 56 protons in its nucleus. This gives us our atomic number of 56, as the atomic number is the number of protons.

The mass number of an atom is the sum of the number of protons and the number of neutrons. We know it has 56 protons and 82 neutrons, so it's mass number is 56+82=138.

Hope this helped!