Question

What is the symbol of an atom containing $20$ protons and $22$ neutrons?

Answer 1

Hint: We have to remember that an atom usually consists of subatomic particles which are electrons, protons and neutrons. An electron carries negative charge; a proton carries positive charge whereas neutrons do not carry any charge on them. The elements are placed in the periodic table according to the increasing atomic number.

Complete step by step answer:
Now before starting this question we must know about the atomic number of the elements present in a periodic table. Number of protons in an atom is equal to the atomic number of an atom. On the other hand, the number of neutrons can be calculated as the difference between mass number and number of protons. In the above question it is given that the number of protons is $20$, thus we can easily identify the atom on this basis; an atom having atomic number $20$ is calcium with an atomic symbol \[Ca\]. The mass number of calcium is $42$, thus we can say that it has $22$ neutrons present in it, as the number of neutrons is the difference between mass number and number of protons. It can be noted that the number of electrons is also equal to the atomic number or can be equal to the number of protons as well since the only difference lies in the charges.

Note:
We need to know that the protons and neutrons are placed inside the nucleus in an atom, whereas electrons revolve around the circular orbits outside the nucleus in an atom. Thus the total charge on an atom is zero as it is balanced by positive charge of proton and negative charge of an electron.