10 is the mass number; 8 is the number of protons; Neutron number is 2; Because mass minus proton equals neutron (10-8=2).

Proton number = atomic number = electron number

Mass number = proton number+neutron number

You must know the mass number and atomic number to find it. )

For example, the atomic number of Na atom is 1 1 and the mass number is 23.

So proton number = electron number = 1 1, mass number = 23, neutron number = 23-112.

Extended data:

Three equations in atoms: nuclear charge number = proton number = extranuclear electron number = atomic number.

Proton number+neutron number ≈ relative atomic mass

Atoms consist of nuclei and extranuclear electrons.

Number of protons (Z)= number of electrons outside the cation nucleus+number of charges of the cation.

Number of protons (Z)= number of extranuclear electrons of anion-number of charges of anion.

Mass number (A)= proton number (Z)+ neutron number (n)

Baidu encyclopedia-proton number