Question

How do you find the number of protons, electrons, and neutrons of a particular atom, if all you are given is the atomic number and mass number?

Answer 1

Atomic number:

1. It is determined by the total number of protons.
2. The number of protons in each atom of a given element is the same, and hence the atomic number is the same.
3. Number of Protons$=$The atomic Number of the element
4. Example: Carbon has an atomic number$12$, Therefore, it will have $12$ protons in its nucleus.
5. The number of protons and electrons in a neutral atom are the same.. so the Number of electrons$=$number of protons$=$The Atomic Number of the element.

Mass number:

1. The mass number of an atom is calculated by adding the number of protons and neutrons. The letter 'A' stands for it.
2. The nucleus of an atom contains both protons and neutrons, which are referred to as nucleons.
3. Mass number$=$The Number of protons $+$Number of neutrons or we can say that Mass number$=$The Atomic number $+$Number of neutrons
4. Number of neutrons$=$Atomic mass $-$ Mass number
5. Example: For boron atomic number$=5$ and atomic mass$=11$, Therefore, the number of neutrons$=11-5\Rightarrow 6$.