How many electrons are there in the atom with a mass number of 66 and n = 35?

31

Explanation:

Given parameters:

Mass number  = 66

 Number of electrons  = 35

Unknown:

Number of electrons

Solution:

In an atom, the number of protons and electrons are the same. In ions, there is a difference between the two numbers.

For this problem, once we can find the number of protons, it is therefore the number of electrons.

 Mass number = number of protons + number of neutrons

  Insert the parameters and solve;

     66  = number of protons + 35

    Number of protons  = 66  - 35  = 31

So the number of electrons is 31