Question

Composition of the nuclei of two atomic species X and Y are given as under:
Protons = 6 (X) ; 6 (Y)
Neutrons = 6 (X) ; 8 (Y)
Given the mass numbers of X and Y, what is the relation between the two species?

Answer 1

The mass number of an element is always equal to the number of neutrons( neutral particles) and the protons (positively charged particles) present in the nucleus and the atomic number is always equal to the number of the protons present in the nucleus and the number of electrons ( negatively charged particles) in an elements is always equal to the number of protons in the nucleus to maintain the electrical neutrality of the element.

Complete step by step answer:
First of all, let’s discuss what electrons, protons and neutrons. An atom is the smallest particle of an element which combines to form molecules and molecules combine to form compounds.
An atom consists of electrons , protons and neutrons. Electrons are negatively charged particles that revolve around the nucleus , protons are positively charged p[articles present in the nucleus due to which the nucleus acquires positive charge and neutrons are the neutral particles which are also present in the nucleus.
Atomic number of an element (Z) is always equal to the number of protons in the nucleus. Example: sodium has 11 protons in the nucleus. So ,its atomic number is 11.
The number of electrons in an atom is always equal to the number of protons in the nucleus. Example: sodium has 11 protons, the number of electrons in it also 11.
Mass number of an element(A) is always equal to the sum of the protons and the neutrons present in the nucleus.
Now, considering the given statement;
Number of protons in X = 6
Number of neutrons in X = 6
The mass number of X = 6 + 6
= 12

Similarly,
Number of protons in Y = 6
Number of neutrons in Y = 8
The mass number of Y= 6 + 8
= 14
Since both the atomic species X and Y have the same number of protons i.e. 6 then their atomic number is also the same as discussed above. We know that the element which has the atomic number 6 is carbon . so , this means that they both are the isotopes of carbon. Isotopes are the elements having the same atomic number (Z) but different mass number (A).

Note: the neutrons and protons present in the nucleus are collectively called as the nucleons and the neutrons have slightly greater mass than the mass of the protons. Neutrons are neutrally charged particles whereas the protons are the positively charged particles.