Question

From the symbol ${}_{40}{}^{20}\mathrm{Ca}$ state:

Atomic number

Answer 1

Atomic number:

1. It is defined as the sum of all the protons present in an atom.
2. Atomic number can never be negative or fractional.

General representation of an element: ${}_{\mathrm{Z}}{}^{\mathrm{A}}\mathrm{X}$

Here,

A = mass number of element X

Z= atomic number or number of protons in X

So,

In ${}_{40}{}^{20}\mathrm{Ca}$, the mass number of Calcium is 40 and its atomic number is 20.

Hence, the atomic number of ${}_{40}{}^{20}\mathrm{Ca}$ is 20.