Question

How many neutrons are present in the nucleus of the phosphorus atom?

Answer 1

Hint: In order to calculate the number of neutrons present in the nucleus of the phosphorus atom, we should know about the atomic number and the mass number of the phosphorus atom. Knowing that it will be easy to calculate the neutrons present in phosphorus atoms.

Complete answer:
First let us see what an atom is. All the matter is composed of tiny particles, which are called atoms. Atoms have subatomic particles present in it such as protons, neutrons, electrons. An atom consists of a nucleus with the electrons revolving around it. The atom’s nucleus is made up of the protons and neutrons. The protons and neutrons together are called nucleons.
Let us first understand about the atomic number. Atomic number is the total number of the electrons or protons present in the atoms and it is represented by the symbol Z.
Now let us move onto the mass number. Mass number is the total number of protons and neutrons together present in the nucleus of an atom and it is denoted by the symbol A.
Now let us consider the Phosphorus atom. Phosphorus is having an atomic number of 15 and a mass number of 31.
In order to find the number of neutrons present in the phosphorus atom, we have to subtract the number of protons from the mass number.
We can obtain the number of protons from the atomic number because the atomic number is the total number of electrons or protons.
We know that the atomic number of phosphorus is 15, therefore the number of protons present is also 15.
The number of neutrons = Mass number of phosphorus atom – number of protons
The number of neutrons present in phosphorus atom= 31 – 15 = 16.
Therefore, the number of neutrons present in the phosphorus atom is 16.

Note: We have to remember that the mass of the electron is so small that it is negligible while calculating the mass number of an atom. We will only consider the mass of the proton and the neutrons.