A Se atom has a mass number of 79 . Determine the number of neutrons, protons, and electrons in this neutral isotope

Question

number of neutrons:

number of protons:

number of electrons:

Answer 1

Hi Brian,

The number of neutrons + the number of protons = the mass number

Looking at the Periodic Table, we see that Se has an atomic number of 34. So, we can substitute into the above relationship and solve for the unknown quantity:

The number of neutrons + 34 = 79

Rearranging give:

The number of neutrons = 45

We already determined that the number of protons of a Se atom is 34.

Now, since the Se atom is neutral, the number of protons = number of electrons

Thus the atom has 34 electrons