A neutral isotope of zinc has a nucleus containing 36 neutrons and has an overall mass num… — Armed Services Vocational Aptitude Battery (ASVAB)

A neutral isotope of zinc has a nucleus containing $36$ neutrons and has an overall mass number of $66$ . During a chemical reaction, this atom forms a $\text{Zn}^{2+}$ cation by losing $2$ electrons. Calculate the total number of electrons present in the $\text{Zn}^{2+}$ ion.

Answer: 28 electrons

Answer

28 electrons

The mass number (

66

) minus the number of neutrons (

36

) gives an atomic number of

30

, which corresponds to

30

protons. A neutral atom has

30

electrons, and losing

2

electrons to become

\text{Zn}^{2+}

leaves exactly

28

electrons.

Step-by-Step Solution

Calculate the number of protons (atomic number) in the zinc atom

30 protons

The mass number equals the sum of protons and neutrons (

A = Z + N

), so

Z = 66 - 36 = 30

Calculate the remaining electrons in the

\text{Zn}^{2+}

cation

28 electrons

A neutral atom has an equal number of protons and electrons (30). A

+2

charge indicates the loss of 2 electrons (

30 - 2 = 28

Key Concept

Subatomic particle counts in isotopes and monatomic ions

Estimated Time:1m 0s

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