Chapter 2, Problem 2.29P

a)

Interpretation Introduction

Interpretation:Whether the pair $\text{H}$ and $\text{H}\text{e}$ have same number of protons, neutrons and electrons should be determined.Also,whether the pair $\text{H}{\text{ and }}_2^3\text{He}$ have same mass number $\left(\text{A}\right)$ , numbers of neutrons $\left(\text{N}\right)$ and numbers of protons $\left(\text{Z}\right)$ should be determined.

Concept introduction:The nuclide symbol of an atom is represented as follows:

  $\text{X}$

Where,

• Z is an atomic number.
• A is the mass number.
• $\text{X}$is the isotope of any element.

Mass number of a nucleus is the total number of neutrons and protons. The number of protons and electrons are same in neutral species.

Isotopes are species that have same atomic number but different mass number.The number of protonsis determined by the atomic number $\left(\text{Z}\right)$ .

Mass number $\left(\text{A}\right)$ of any isotope of an element is total number of neutrons $\left(\text{N}\right)$ and total number of protons $\left(\text{Z}\right)$ .The numbers of neutronsare determined by difference between mass number and number of protons.

Explanation of Solution

Number of protons $\left(\text{Z}\right)$ in the pair $\text{H}$ and $\text{H}\text{e}$ is 1 and 2 respectively.

Number of electrons in the pair $\text{H}$ and $\text{H}\text{e}$ is 1 and 2 respectively.As to maintain neutrality, number of electrons will be the same as number of protons $\left(\text{Z}\right)$ .

The number of neutrons in $\text{H}$ is calculated as follows:

  $\begin{array}{c}\text{Number of neutron}\left(\text{N}\right)\text{= Mass Number}\left(\text{A}\right)-\text{Number of protons}\left(\text{Z}\right)\\ =\left(3-1\right)\\ =2\end{array}$

The number of neutrons in $\text{H}\text{e}$ is calculated as follows:

  $\begin{array}{c}\text{Number of neutron}\left(N\right)\text{= Mass Number}\left(\text{A}\right)-\text{Number of protons}\left(\text{Z}\right)\\ =\left(3-2\right)\\ =1\end{array}$

Therefore, $\text{H}$ and $\text{H}\text{e}$ has same mass value $\left(\text{A}\right)$ .

b)

Interpretation Introduction

Interpretation:Whether the pair $\text{C}$ and ${}_7^{15}\text{N}$ have same number of protons, neutrons and electrons should be determined.Also,whether the pair $\text{C}{\text{ and }}_7^{15}\text{N}$ have same mass number $\left(\text{A}\right)$ , numbers of neutrons $\left(\text{N}\right)$ and numbers of protons $\left(\text{Z}\right)$ should be determined.

Concept introduction:The nuclide symbol of an atom is represented as follows:

  $\text{X}$

Where,

• Z is an atomic number.
• A is the mass number.
• $\text{X}$is the isotope of any element.

The mass number of a nucleus is the total number of neutrons and protons. The number of protons and electrons are same in neutral species.

Isotopes are species that have same atomic number but different mass number. The number of protons is determined by the atomic number $\left(\text{Z}\right)$ .

Mass number $\left(\text{A}\right)$ of any isotope of an element is total number of neutrons $\left(\text{N}\right)$ and total number of protons $\left(\text{Z}\right)$ . The numbers of neutrons are determined by difference between mass number and number of protons.

Explanation of Solution

Number of protons $\left(\text{Z}\right)$ in the pair $\text{C}$ and ${}_7^{15}\text{N}$ are 6 and 7 respectively.

Number of electrons in the pair $\text{C}$ and ${}_7^{15}\text{N}$ are are 6 and 7 respectively.As to maintain neutrality, the numbers of electrons will be the same as number of protons $\left(\text{Z}\right)$ .

The number of neutrons in $\text{C}$ is calculated as follows:

  $\begin{array}{c}\text{Number of neutron}\left(N\right)\text{= Mass Number}\left(\text{A}\right)-\text{Number of protons}\left(\text{Z}\right)\\ =\left(14-6\right)\\ =8\end{array}$

The number of neutrons in ${}_7^{15}\text{N}$ is calculated as follows:

  $\begin{array}{c}\text{Number of neutron}\left(N\right)\text{= Mass Number}\left(\text{A}\right)-\text{Number of protons}\left(\text{Z}\right)\\ =\left(15-7\right)\\ =8\end{array}$

Therefore, $\text{C}$ and ${}_7^{15}\text{N}$ pair has same $\text{N}$ value.

c)

Interpretation Introduction

Interpretation:Whether the pair $\text{F}$ and ${}_9^{18}\text{F}$ have same number of protons, neutrons and electrons should be determined. Also, whether the pair $\text{F}{\text{ and }}_9^{18}\text{F}$ have same mass number $\left(\text{A}\right)$ , numbers of neutrons $\left(\text{N}\right)$ and numbers of protons $\left(\text{Z}\right)$ should be determined.

Concept introduction:The nuclide symbol of an atom is represented as follows:

  $\text{X}$

Where,

• Z is an atomic number.
• A is the mass number.
• $\text{X}$is the isotope of any element.

The mass number of a nucleus is the total number of neutrons and protons. The number of protons and electrons are same in neutral species.

Isotopes are species that have same atomic number but different mass number. The number of protons is determined by the atomic number $\left(\text{Z}\right)$ .

Mass number $\left(\text{A}\right)$ of any isotope of an element is total number of neutrons $\left(\text{N}\right)$ and total number of protons $\left(\text{Z}\right)$ . The numbers of neutrons are determined by difference between mass number and number of protons.

Explanation of Solution

Number of protons $\left(\text{Z}\right)$ in the pair $\text{F}$ and ${}_9^{18}\text{F}$ are 9 and 9 respectively.

Number of electrons in the pair $\text{F}$ and ${}_9^{18}\text{F}$ are 9and 9 respectively.As to maintain neutrality, the numbers of electrons will be the same as the number of protons $\left(\text{Z}\right)$ .

The number of neutrons in $\text{F}$ is calculated as follows:

  $\begin{array}{c}\text{Number of neutron}\left(N\right)\text{= Mass Number}\left(\text{A}\right)-\text{Number of protons}\left(\text{Z}\right)\\ =\left(19-9\right)\\ =10\end{array}$

The number of neutrons in $\text{F}$ is calculated as follows:

  $\begin{array}{c}\text{Number of neutron}\left(N\right)\text{= Mass Number}\left(\text{A}\right)-\text{Number of protons}\left(\text{Z}\right)\\ =18-9\\ =9\end{array}$

Therefore, $\text{F}$ and ${}_9^{18}\text{F}$ pair has same $\text{Z}$ value.