Chapter 4, Problem 21E

Interpretation Introduction

(a)

Interpretation:

The number of neutrons in an atom of $\text{hydrogen-1}$ is to be predicted.

Concept introduction:

The atomic number of an atom is equal to the number of protons in an atom. Mass number or atomic mass of an atom can be calculated by taking the sum of atomic number and number of neutrons.

Answer to Problem 21E

The number of neutrons in atom of $\text{hydrogen-1}$ is $0$.

Explanation of Solution

The mass number of $\text{hydrogen-1}$ is $1$ and atomic number is also $1$.

The number of neutrons is calculated by the formula shown below.

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

Substitute the values of mass number and atomic number in the above equation.

$\begin{array}{rll}\text{Number}\text{of}\text{neutrons}& =& 1-1\\ & =& 0\end{array}$

Thus, the number of neutrons in atom of $\text{hydrogen-1}$ is $0$.

Conclusion

The number of neutrons in an atom of $\text{hydrogen-1}$ is $0$.

Interpretation Introduction

(b)

Interpretation:

The number of neutrons in an atom of $\text{carbon-13}$ is to be predicted.

Concept introduction:

The atomic number of an atom is equal to the number of protons in an atom. Mass number or atomic mass of an atom can be calculated by taking the sum of atomic number and number of neutrons.

Answer to Problem 21E

The number of neutrons in an atom of $\text{carbon-13}$ is $\text{7}$.

Explanation of Solution

The mass number of $\text{carbon-13}$ is $\text{13}$ and atomic number is $\text{6}$.

The number of neutrons is calculated by the formula shown below.

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

Substitute the values of mass number and atomic number in the above equation.

$\begin{array}{rll}\text{Number}\text{of}\text{neutrons}& =& 13-6\\ & =& 7\end{array}$

Thus, the number of neutrons in atom of $\text{carbon-13}$ is $\text{7}$.

Conclusion

The number of neutrons in an atom of $\text{carbon-13}$ is $\text{7}$.

Interpretation Introduction

(c)

Interpretation:

The number of neutrons in an atom of $\text{cobalt-59}$ is to be predicted.

Concept introduction:

The atomic number of an atom is equal to the number of protons in an atom. Mass number or atomic mass of an atom can be calculated by taking the sum of atomic number and number of neutrons.

Answer to Problem 21E

The number of neutrons in an atom of $\text{cobalt-59}$ is $32$.

Explanation of Solution

The mass number of $\text{cobalt-59}$ is $\text{59}$ and atomic number is $\text{27}$.

The number of neutrons is calculated by the formula shown below.

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

Substitute the values of mass number and atomic number in the above equation.

$\begin{array}{rll}\text{Number}\text{of}\text{neutrons}& =& 59-27\\ & =& 32\end{array}$

Thus, the number of neutrons in atom of $\text{cobalt-59}$ is $32$.

Conclusion

The number of neutrons in an atom of $\text{cobalt-59}$ is $32$.

Interpretation Introduction

(d)

Interpretation:

The number of neutrons in an atom of $\text{iodine-127}$ is to be predicted.

Concept introduction:

The atomic number of an atom is equal to the number of protons in an atom. Mass number or atomic mass of an atom can be calculated by taking the sum of atomic number and number of neutrons.

Answer to Problem 21E

The number of neutrons in an atom of $\text{iodine-127}$ is $74$.

Explanation of Solution

The mass number of $\text{iodine-127}$ is $\text{127}$ and atomic number is $\text{53}$.

The number of neutrons is calculated by the formula shown below.

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

Substitute the values of mass number and atomic number in the above equation.

$\begin{array}{rll}\text{Number}\text{of}\text{neutrons}& =& 127-53\\ & =& 74\end{array}$

Thus, the number of neutrons in an atom of $\text{iodine-127}$ is $74$.

Conclusion

The number of neutrons in an atom of $\text{iodine-127}$ is $74$.