It is equal to the no. of electrons in the atom. It is called the atomic number.

Atomic weight in atomic mass units = the number of protons + the number of neutrons.

The number of protons is your atomic number. Subtract that from the atomic weight for the number of neutrons.

It has 10 neutrons since the atomic number is equal to the number of protons and the isotope number is the number of neutrons and protons together.

The number of feet is not the same as the number of inches.

In length, inches = feet * 12

The number of protons in the nucleus of an element gives that element its ATOMIC NUMBER.