Chapter 2, Problem 23QP

Indicate the number of protons, neutrons, and electrons in each of the following species: $\text{N}\text{,}\text{S}\text{,}\text{C}\text{u,}\text{B}\text{a,}\text{W}\text{,}\text{H}\text{g}\text{.}$

Interpretation Introduction

Interpretation: The numbers of protons, neutrons, and electrons in the givens nuclei areto be determined.

Concept introduction:

The number of neutrons in an atom is defined as the difference between the mass number and the number of protons.

The number of protons and electrons are the same for an uncharged nucleus, which is equal to the atomic number of an element.

Answer to Problem 23QP

Solution:

For ${}_{\text{7}}^{\text{15}}\text{N}$:

Number of neutrons $\text{= 8}$

Number of protons $\text{= }$ Number of electrons $\text{= 7}$

For ${}_{\text{16}}^{\text{33}}\text{S}$:

Number of neutrons $\text{= 17}$

Number of protons $\text{= }$ Number of electrons $\text{= 16}$

For ${}_{\text{29}}^{\text{63}}\text{Cu}$:

Number of neutrons $\text{= 34}$

Number of protons $\text{= }$ Number of electrons $\text{= 29}$

For ${}_{\text{38}}^{\text{84}}\text{Sr}$:

Number of neutrons $\text{= 46}$

Number of protons $\text{= }$ Number of electrons $\text{= 38}$

For ${}_{\text{56}}^{\text{130}}\text{Ba}$:

Number of neutrons $\text{= 74}$

Number of protons $\text{= }$ Number of electrons $\text{= 56}$

For ${}_{\text{74}}^{\text{186}}\text{W}$:

Number of neutrons $\text{= 112}$

Number of protons $\text{= }$ Number of electrons $\text{= 74}$

For ${}_{\text{80}}^{\text{202}}\text{Hg}$:

Number of neutrons $\text{= 122}$

Number of protons $\text{= }$ Number of electrons $\text{= 80}$

Explanation of Solution

For ${}_{\text{7}}^{\text{15}}\text{N}$:

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

From the periodic table, the atomic number of nitrogen is $7$.

Thus, the number of protons is equal to the atomic number that is equal to $7$.

For ${}_{\text{16}}^{\text{33}}\text{S}$:

$\begin{array}{c}\text{Number of neutrons}= \text{Mass number }\left(A\right)-\text{Number of protons}\\ =33-16\\ =17 \end{array}$

From the periodic table, the atomic number of sulfur is $16$.

Thus, the number of protons is equal to the atomic number that is equal to $16$.

For ${}_{\text{29}}^{\text{63}}\text{Cu}$:

$\begin{array}{c}\text{Number of neutrons}= \text{Mass number }\left(A\right)-\text{Number of protons}\\ =63-29\\ =34 \end{array}$

From the periodic table, the atomic number of copper is $29$.

Thus, the number of protons is equal to the atomic number that is equal to $29$.

For ${}_{\text{38}}^{\text{84}}\text{Sr}$:

$\begin{array}{c}\text{Number of neutrons}= \text{Mass number }\left(A\right)-\text{Number of protons}\\ =84-38\\ =46 \end{array}$

From the periodic table, the atomic number of strontiumis $38$.

Thus, the number of protons is equal to the atomic number that is equal to $38$.

For ${}_{\text{56}}^{\text{130}}\text{Ba}$:

$\begin{array}{c}\text{Number of neutrons}= \text{Mass number }\left(A\right)-\text{Number of protons}\\ =130-56\\ =74 \end{array}$

From the periodic table, the atomic number of bariumis $56$.

Thus, the number of protons is equal to the atomic number that is equal to $56$.

For ${}_{\text{74}}^{\text{186}}\text{W}$:

$\begin{array}{c}\text{Number of neutrons}= \text{Mass number }\left(A\right)-\text{Number of protons}\\ =186-74\\ =112 \end{array}$

From the periodic table, the atomic number of tungstenis $74$.

Thus, the number of protons is equal to the atomic number that is equal to $74$.

For ${}_{\text{80}}^{\text{202}}\text{Hg}$:

$\begin{array}{c}\text{Number of neutrons}= \text{Mass number }\left(A\right)-\text{Number of protons}\\ =202-80\\ =122 \end{array}$

From the periodic table, the atomic number of mercuryis $80$.

Thus, the number of protons is equal to the atomic number that is equal to $80$.

Conclusion

The numbers of protons, neutrons, and electrons in the various nuclei arecalculated.