Chapter 5, Problem 22PE

(a)

Interpretation Introduction

Interpretation:

The number of protons, neutrons and electrons in ${}^{\text{54}}\text{Fe}$ has to be given.

Concept Introduction:

Mass number is the sum of the protons and neutrons in the nucleus.

Atomic number is the number of protons present in the nucleus.

For an element $\text{E,}$ the top left number represents the mass number and the bottom left number represents the atomic number.

The letter A represents mass number.

The letter Z represents atomic number.

Answer to Problem 22PE

The number of protons in ${}^{\text{54}}\text{Fe}$ is $\text{26}\text{.}$

The number of electrons in ${}^{\text{54}}\text{Fe}$ is $\text{26}\text{.}$

The number of neutrons in ${}^{\text{54}}\text{Fe}$ is $\text{28}\text{.}$

Explanation of Solution

The atomic number of ${}^{\text{54}}\text{Fe}$ is $\text{26}\text{.}$

The mass number of ${}^{\text{54}}\text{Fe}$ is $\text{54}\text{.}$

Atomic number of an element tells about the number of protons present.

  $\text{Atomic}\text{number=Number}\text{of}\text{protons}$

The number of protons present will be equal to the number of electrons.

  $\text{Number}\text{of}\text{protons=Number}\text{of}\text{electrons}$

Atomic number of ${}^{\text{54}}\text{Fe}$ is $\text{26}\text{.}$  Therefore, the number of protons is $\text{26}\text{.}$  The number of electrons is $\text{26}\text{.}$

The number of neutrons is the difference between the mass number and the atomic number.

  $\text{Number}\text{of}\text{neutrons=Mass}\text{number-Atomic}\text{number}$

The number of neutrons is calculated as,

  Number of neutrons=$\text{54-26}$

  Number of neutrons=$\text{28}$

The number of protons in ${}^{\text{54}}\text{Fe}$ is $\text{26}\text{.}$

The number of electrons in ${}^{\text{54}}\text{Fe}$ is $\text{26}\text{.}$

The number of neutrons in ${}^{\text{54}}\text{Fe}$ is $\text{28}\text{.}$

(b)

Interpretation Introduction

Interpretation:

The number of protons, neutrons and electrons in ${}^{\text{23}}\text{Na}$ has to be given.

Concept Introduction:

Refer to part (a).

Answer to Problem 22PE

The number of protons in ${}^{\text{23}}\text{Na}$ is $\text{11}\text{.}$

The number of electrons in ${}^{\text{23}}\text{Na}$ is $\text{11}\text{.}$

The number of neutrons in ${}^{\text{23}}\text{Na}$ is $\text{12}\text{.}$

Explanation of Solution

The atomic number of ${}^{\text{23}}\text{Na}$ is $\text{11}\text{.}$

The mass number of ${}^{\text{23}}\text{Na}$ is $\text{23}\text{.}$

Atomic number of an element tells about the number of protons present.

  $\text{Atomic}\text{number=Number}\text{of}\text{protons}$

The number of protons present will be equal to the number of electrons.

  $\text{Number}\text{of}\text{protons=Number}\text{of}\text{electrons}$

Atomic number of ${}^{\text{23}}\text{Na}$ is $\text{11}\text{.}$  Therefore, the number of protons is $\text{11}\text{.}$  The number of electrons is $\text{11}\text{.}$

The number of neutrons is the difference between the mass number and the atomic number.

  $\text{Number}\text{of}\text{neutrons=Mass}\text{number-Atomic}\text{number}$

The number of neutrons is calculated as,

  Number of neutrons=$\text{23-11}$

  Number of neutrons=$\text{12}$

The number of protons in ${}^{\text{23}}\text{Na}$ is $\text{11}\text{.}$

The number of electrons in ${}^{\text{23}}\text{Na}$ is $\text{11}\text{.}$

The number of neutrons in ${}^{\text{23}}\text{Na}$ is $\text{12}\text{.}$

(c)

Interpretation Introduction

Interpretation:

The number of protons, neutrons and electrons in ${}^{79}\text{Br}$ has to be given.

Concept Introduction:

Refer to part (a).

Answer to Problem 22PE

The number of protons in ${}^{79}\text{Br}$ is $\text{35}\text{.}$

The number of electrons in ${}^{79}\text{Br}$ is $\text{35}\text{.}$

The number of neutrons in ${}^{79}\text{Br}$ is $\text{44}\text{.}$

Explanation of Solution

The atomic number of ${}^{79}\text{Br}$ is $\text{35}\text{.}$

The mass number of ${}^{79}\text{Br}$ is $\text{79}\text{.}$

Atomic number of an element tells about the number of protons present.

  $\text{Atomic}\text{number=Number}\text{of}\text{protons}$

The number of protons present will be equal to the number of electrons.

  $\text{Number}\text{of}\text{protons=Number}\text{of}\text{electrons}$

Atomic number of ${}^{79}\text{Br}$ is $\text{35}\text{.}$  Therefore, the number of protons is $\text{35}\text{.}$  The number of electrons is $\text{35}\text{.}$

The number of neutrons is the difference between the mass number and the atomic number.

  $\text{Number}\text{of}\text{neutrons=Mass}\text{number-Atomic}\text{number}$

The number of neutrons is calculated as,

  Number of neutrons=$\text{79-35}$

  Number of neutrons=$\text{44}$

The number of protons in ${}^{79}\text{Br}$ is $\text{35}\text{.}$

The number of electrons in ${}^{79}\text{Br}$ is $\text{35}\text{.}$

The number of neutrons in ${}^{79}\text{Br}$ is $\text{44}\text{.}$

(d)

Interpretation Introduction

Interpretation:

The number of protons, neutrons and electrons in ${}^{\text{31}}\text{P}$ has to be given.

Concept Introduction:

Refer to part (a).

Answer to Problem 22PE

The number of protons in ${}^{\text{31}}\text{P}$ is $\text{15}\text{.}$

The number of electrons in ${}^{\text{31}}\text{P}$ is $\text{15}\text{.}$

The number of neutrons in ${}^{\text{31}}\text{P}$ is $\text{16}\text{.}$

Explanation of Solution

The atomic number of ${}^{\text{31}}\text{P}$ is $\text{15}\text{.}$

The mass number of ${}^{\text{31}}\text{P}$ is $\text{31}\text{.}$

Atomic number of an element tells about the number of protons present.

  $\text{Atomic}\text{number=Number}\text{of}\text{protons}$

The number of protons present will be equal to the number of electrons.

  $\text{Number}\text{of}\text{protons=Number}\text{of}\text{electrons}$

Atomic number of ${}^{\text{31}}\text{P}$ is $\text{15}\text{.}$  Therefore, the number of protons is $\text{15}\text{.}$  The number of electrons is $\text{15}\text{.}$

The number of neutrons is the difference between the mass number and the atomic number.

  $\text{Number}\text{of}\text{neutrons=Mass}\text{number-Atomic}\text{number}$

The number of neutrons is calculated as,

  Number of neutrons=$\text{31-15}$

  Number of neutrons=$\text{16}$

The number of protons in ${}^{\text{31}}\text{P}$ is $\text{15}\text{.}$

The number of electrons in ${}^{\text{31}}\text{P}$ is $\text{15}\text{.}$

The number of neutrons in ${}^{\text{31}}\text{P}$ is $\text{16}\text{.}$