Question

Give the nuclear symbol for the isotope of gallium, ga, that contains 40 neutrons per atom. Replace the question marks with the proper integers.

Answer 1

The nuclear symbol of an element have three parts namely:  

1. the symbol of an element
2. mass number of the element
3. atomic number of the element

The general representation is as:

$_{Z}^{A}X$

where X is the chemical symbol of the element, A is mass number of the element that is total number of neutrons and protons in the nucleus of an atom, and Z is atomic number of the element that is number of protons in the atom.

Element = Gallium, $Ga$    (given)

Number of neutrons = 40 (given)

Let the nuclear symbol be $_{?}^{?}Ga$. So, we need to determine the values of "?" in the symbol.

Atomic number of Gallium, $Ga$ = 31

Since, atomic number = Number of protons.

So, number of protons of Gallium, $Ga$ = 31

Mass number = number of protons + number of neutrons

Substituting the values:

Mass number = $31+40 = 71$

So, the nuclear symbol is $_{31}^{71}Ga$.