Question

In 4 2 He 24He , what does the number 4 indicate?

Answer 1

The number 4 indicates the mass number of the element.

Step-by-step explanation:

The mass is defined as the number of nucleons in the nucleus of the element.

Let an element is
`X_(Z)^(A)`

Here Z is the number of protons in the nucleus

A be the number of nucleons in the nucleus

The number of nucleons is the sum of number of protons and the number of neutrons.

So, the number of protons in the nucleus are Z, number of neutrons are A - Z in the nucleus.

Thus, 4 indicates the sum of number of protons and the neutrons.

Answer 2

The 4 indicates the sum of the protons and neutrons and electrons present in the atom. The superscript (number on top) shows the atomic mass, the sum of the protons and neutrons and the electrons. The subscript (number on the bottom) shows the atomic number, or the number of protons. All of these numbers are on the left side of the atomic symbol.