Question

If an atom has a mass number of 118 and atomic number of 50, how many neutrons are present in the nucleus.

Answer 1

Hint In order to calculate the number of neutrons present in the nucleus of the tin atom, we must be knowing about the atomic number and the mass number of the phosphor atom. From this we can easily calculate the neutrons present.

Complete step by step solution:
First let us see what an atom is. All the matter is composed of tiny particles, which are called atoms. Atoms have many subatomic particles such as protons, neutrons, electrons, alpha and beta particles. An atom is made up of nucleus with the electrons revolving around it. The nucleus is composed of the protons and neutrons. The protons and neutrons together are called nucleons. Proton is one of the subatomic particles which has a positive charge. The neutron will be having a neutral charge. The electron will also have a charge which is negative.
Let us first understand about the atomic number. The total number of the electrons or protons present in the atoms are called the atomic number, which is represented by the symbol Z.
Now let us move onto the mass number. The total number of protons and neutrons together present in the nucleus of an atom will give the mass number, which is denoted by the symbol A.
Now let us consider the tin atom. Tin atom has an atomic number of 50 and a mass number of 118.
In order to find the number of neutrons present in the tin 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 tin is 50, therefore the number of protons present is also 50.
The number of neutrons = Mass number of tin atoms – number of protons
The number of neutrons of tin atoms = 118-50 = 68.
Therefore, the number of neutrons present in the tin atom is 68.

Note: We have to remember that all protons, neutrons and electrons will be having different charges.
- The charge of the proton is positive.
- The charge of a neutron is neutral.
- The charge of the electron is negative.