The name for it is Mass Number of an Isotope.
Atomic number is the bottom number on an element in the periodic table. It is the proton number, so tells you how much protons are in an element. EXTRA: you can find the neutron number by subtracting the mass number from the proton number.
The proton number is also known as the atomic number when referring to the periodic table. It represents the number of protons in the nucleus of an atom, which determines its chemical properties and its unique place on the periodic table.
Find the weight on the periodic table then subtract the proton numbers.
Mass no-the no of proton=no of neutron
One way is to consult a copy of "The Periodic Table of the Elements". Great Q'n!
Periodic table
When a neutron -> proton, it is called a Beta - (minus) decay.
the decay of neutron into proton givesz small praticle called negative beta particle
3 in each
neutron, proton and electron
neutron
Of the common sub-atomic particles, both the proton and the neutron have mass numbers of 1.