Chapter 4, Problem 125A

Interpretation Introduction

Interpretation:

The mass number for each isotope of zirconium needs to be determined.

Concept introduction:

The mass number of different isotopes is different because the isotope of the elements has the same number of protons but different numbers of the neutrons. Formula to calculate atomic mass,

ATOMIC MASS = NUMBER OF PROTONS $+$ NUMBER OF NEUTRONS.

The mass number is equal to the atomic mass of the isotope.

Answer to Problem 125A

The mass number for each isotope is ${\text{Zr}}^{90}$ = $90$, ${\text{Zr}}^{91}$ = $91$, ${\text{Zr}}^{92}$ = $92$, ${\text{Zr}}^{94}$ = $94$, ${\text{Zr}}^{96}$ = $96$.

Explanation of Solution

The given table gives information about each isotope of the zirconium and easy to find out the mass number.

The Relative abundance of zirconium isotopes
Element	Mass (amu)	Abundance (%)
Zirconium-90	$89.905$	$51.45$
Zirconium-91	$90.906$	$11.22$
Zirconium-92	$91.905$	$17.15$
Zirconium-94	$93.906$	$17.38$
Zirconium-96	$95.908$	$2.8$

From the given table the mass number of each isotope of zirconium − The Mass number of ${\text{Zr}}^{90}$ = $90$.

The Mass number of ${\text{Zr}}^{91}$ = $91$.

The Mass number of ${\text{Zr}}^{92}$ = $92$.

The Mass number of ${\text{Zr}}^{94}$ = $94$.

The Mass number of ${\text{Zr}}^{96}$ = $96$.

Conclusion

The mass number is different for each isotope of the elements. So, the isotope is represented with their mass number.