Question

How would you give the nuclear symbol for the isotope of gallium, \[Ga\], that contains \[40\] neutrons per atom?

Answer 1

Hint: Nuclear symbol is short notation for the corresponding element. The nuclear symbol is written along with the atomic number and mass number.

Complete step by step answer:
Gallium is an element in the periodic table with atomic number \[31\] and electronic configuration \[\left[ {Ar} \right]3{d^{10}}4{s^2}4{p^1}\]. The configuration of the electrons indicates that it is a p-block element. It belongs to the boron family.
The mass number of gallium is \[69\] and the number of protons in gallium is \[31\]. Thus the number of neutrons in gallium is \[69 - 31 = 38\].
Gallium exists in nature as two isotopes. Isotopes of an element are the same element which possesses the same atomic number but different mass number. This is also said as the same elements which differ in the number of neutrons.
For writing the nuclear symbol of an isotope \[X\], we need the atomic number \[Z\] and the mass number\[A\]. The atomic number is written as the subscript and the mass number is written as the superscript. The element is represented as \[{}_Z^AX\] .
In this case, the isotope contains \[40\]neutrons. The number of protons present in gallium is equal to the atomic number i.e. \[31\]. Thus the mass number of gallium is \[31 + 40 = 71\].
Thus we have \[A = 71\] and \[Z = 31\]. Hence nuclear symbol for the isotope of gallium, \[Ga\], that contains \[40\] neutrons per atom is

Note: The two isotopes of gallium have mass numbers \[69\] and \[71\] respectively. So the numbers of neutrons are \[38\] and \[40\] respectively. The isotopes which are more stable only exist in abundance. The modern periodic table contains the symbolic representation of all the elements along with atomic and mass numbers.