Chapter 18, Problem 21AE

(a)

Interpretation Introduction

Interpretation:

Number of protons, number of electrons and number of neutrons in $\text{chromium-}51$ has to be given.

Concept Introduction:

Number of protons is determined by the atomic number $\left(\text{Z}\right)$. To maintain neutrality of a nucleus number of protons and number electrons will be same. Number of neutrons is determined by difference in number of protons and total mass number.

The nuclide symbol of an atom is represented as follows:

  $\text{X}$

Here,

$\text{Z}$ is an atomic number.

$\text{A}$ is mass number.

$\text{X}$ is isotope of any element.

Answer to Problem 21AE

Number of protons in $\text{chromium-}51$ is 24. Number of neutrons in $\text{chromium-}51$ is 27. Number of electrons in $\text{chromium-}51$ is 24.

Explanation of Solution

Atomic number of $\text{chromium-}51$ is 24 and mass number of $\text{chromium-}51$ is 51. So, number of protons in $\text{chromium-}51$ is 24 and number of electrons in $\text{chromium}-51$ is 24.

The formula to calculate the number of neutrons in $\text{chromium}-51$ is as follows:

  $\text{Number of neutron}\left(\text{N}\right)=\left[\begin{array}{l}\text{Mass Number}\left(\text{A}\right)-\\ \text{Number of protons}\left(\text{Z}\right)\end{array}\right]$        (1)

Substitute 51 for mass number $\left(\text{A}\right)$ and 24 for number of protons $\left(\text{Z}\right)$ in equation(1).

  $\begin{array}{c}\text{Number of neutron}\left(\text{N}\right)=\text{51}-\text{24}\\ =27\end{array}$

Hence, number of neutrons in $\text{chromium-}51$ is 27.

(b)

Interpretation Introduction

Interpretation:

Number of protons, number of electrons and number of neutrons in $\text{holmium-}166$ has to be given.

Concept Introduction:

Refer to part (a)

Answer to Problem 21AE

Number of protons in $\text{holmium-}166$ is 67. Number of neutrons in $\text{holmium-}166$ is 99. Number of electrons in $\text{holmium-}166$ is 67.

Explanation of Solution

Atomic number of $\text{holmium-}166$ is 67 and mass number of $\text{holmium-}166$ is 166. So, number of protons in $\text{holmium-}166$ is 67 and number of electrons in $\text{holmium-}166$ is 67.

The formula to calculate the number of neutrons in $\text{chromium}-51$ is as follows:

  $\text{Number of neutron}\left(\text{N}\right)=\left[\begin{array}{l}\text{Mass Number}\left(\text{A}\right)-\\ \text{Number of protons}\left(\text{Z}\right)\end{array}\right]$        (1)

Substitute 166 for mass number $\left(\text{A}\right)$ and 67 for number of protons $\left(\text{Z}\right)$ in equation(1).

  $\begin{array}{c}\text{Number of neutron}\left(\text{N}\right)=\text{166}-\text{67}\\ =99\end{array}$

Hence, number of neutrons in $\text{holmium-}166$ is 99.

(c)

Interpretation Introduction

Interpretation:

Number of protons, number of electrons and number of neutrons in $\text{palladium-}103$ has to be given.

Concept Introduction:

Refer to part (a)

Answer to Problem 21AE

Number of protons in $\text{palladium-}103$ is 46. Number of neutrons in $\text{palladium-}103$ is 57. Number of electrons in $\text{palladium-}103$ is 46.

Explanation of Solution

Atomic number of $\text{palladium-}103$ is 46 and mass number of $\text{palladium-}103$ is 103. So, number of protons in $\text{palladium-}103$ is 46 and number of electrons in $\text{palladium-}103$ is 46.

The formula to calculate the number of neutrons in $\text{chromium}-51$ is as follows:

  $\text{Number of neutron}\left(\text{N}\right)=\left[\begin{array}{l}\text{Mass Number}\left(\text{A}\right)-\\ \text{Number of protons}\left(\text{Z}\right)\end{array}\right]$        (1)

Substitute 103 for mass number $\left(\text{A}\right)$ and $46$ for number of protons $\left(\text{Z}\right)$ in equation(1).

  $\begin{array}{c}\text{Number of neutron}\left(\text{N}\right)=\text{103}-\text{46}\\ =57\end{array}$

Hence, number of neutrons in $\text{palladium-}103$ is 57.

(d)

Interpretation Introduction

Interpretation:

Number of protons, number of electrons and number of neutrons in  $\text{strontium-}89$ has to be given.

Concept Introduction:

Refer to part (a)

Answer to Problem 21AE

Number of protons in $\text{strontium-}89$ is 38. Number of neutrons in $\text{strontium-}89$ is 51. Number of electrons in $\text{strontium-}89$ is 38.

Explanation of Solution

Atomic number of $\text{strontium-}89$ is 38 and mass number of $\text{strontium-}89$ is 89. So, number of protons in $\text{strontium-}89$ is $38$ and number of electrons in $\text{strontium}-89$ is 38.

The formula to calculate the number of neutrons in $\text{chromium}-51$ is as follows:

  $\text{Number of neutron}\left(\text{N}\right)=\left[\begin{array}{l}\text{Mass Number}\left(\text{A}\right)-\\ \text{Number of protons}\left(\text{Z}\right)\end{array}\right]$        (1)

Substitute 89 for mass number $\text{A}$ and 38 for number of protons $\text{Z}$ in equation(1).

  $\begin{array}{c}\text{Number of neutron}\left(\text{N}\right)\text{= 89}-\text{38}\\ =51\end{array}$

Hence, number of neutrons in $\text{strontium-}89$ is 51.