How to calculate number of electron,proton,neutron - Science - Structure of the Atom

Question

How to calculate number of electron,proton,neutron ?

Kirti Gogia · Accepted Answer

The number of electrons, protons and neutrons in an atom can be
determined from the atomic number and the mass number of the
element The atomic number of an element is equal to the number of
protons present in an atom of the element Since an atom is
electrically neutral, therefore the number of protons are equal to
the number of electrons Thus
atomic number = number of protons = number of electrons
The mass number is equal to the total number of protons and
neutrons present in an atom of the element Thus
mass number = number of protons + number of neutrons
Hence, in an atom
number of electrons = number of protons = atomic number
number of neutrons = mass number - number of protons
= mass number - atomic number
For example, the atomic number of sodium is 11, while its mass
number is 23 So
number of electrons in Na = number of protons = atomic number of
Na = 11
number of neutrons in Na = mass number of Na - atomic number of
Na = 23 - 11 = 12