Chapter 2, Problem 2.19E

Interpretation Introduction

(a)

Interpretation:

The mass number and atomic number for an atom containing nucleus made up of $6$ protons and $6$ neutrons are to be calculated and the symbol for an atom is to be stated.

Concept introduction:

The atomic number of an atom is equal to the number of protons in an atom. Mass number of an atom can be calculated by taking the sum of atomic number and number of neutrons. The general isotopic symbol for an atom is represented as given below.

${}_{\text{x}}^{\text{y}}\text{A}$

Answer to Problem 2.19E

The mass number and atomic number for an atom containing nucleus made up of $6$ protons and $6$ neutrons are $12$ and $6$ respectively. The symbol is represented as ${}_{\text{6}}^{\text{12}}\text{C}$.

Explanation of Solution

The given atom contains $6$ protons and $6$ neutrons. It is known that the atomic number of an atom is equal to the number of protons. Therefore, the atomic number of the given atom is $6$.

The formula to calculate mass number is,

$\text{Mass}\text{number}=\text{Atomic}\text{number}+\text{number}\text{of}\text{neutrons}$

Substitute the values in the above equation.

$\begin{array}{rll}\text{Mass}\text{number}& =& \text{Atomic}\text{number}+\text{number}\text{of}\text{neutrons}\\ & =& \text{6}+\text{6}\\ & =& \text{12}\end{array}$

The general representation of an atom is as follows.

${}_{\text{x}}^{\text{y}}\text{A}$

Where,

• $\text{x}$ represents the atomic number of the atom $\text{A}$.

• $\text{y}$ represents the mass number of the atom $\text{A}$.

The atom with atomic number $6$ is carbon and it has atomic symbol $\text{C}$. The mass number calculated for it, is $12$. Thus, the symbol for carbon can be written as given below.

${}_{\text{6}}^{\text{12}}\text{C}$

Conclusion

The mass number and atomic number for an atom containing nucleus made up of $6$ protons and $6$ neutrons are calculated as $12$ and $6$ respectively. The symbol is represented as ${}_{\text{6}}^{\text{12}}\text{C}$.

Interpretation Introduction

(b)

Interpretation:

The mass number and atomic number for atom containing nucleus made up of $8$ protons and $9$ neutrons are to be calculated and the symbol for an atom is to be stated.

Concept introduction:

The atomic number of an atom is equal to the number of protons in an atom. Mass number of an atom can be calculated by taking the sum of atomic number and number of neutrons. The isotopic symbol for an atom is represented as given below.

${}_{\text{x}}^{\text{y}}\text{A}$

Answer to Problem 2.19E

The mass number and atomic number for an atom containing nucleus made up of $8$ protons and $9$ neutrons are $17$ and $8$ respectively. The symbol is represented as ${}_{\text{8}}^{\text{17}}\text{O}$.

Explanation of Solution

The given atom contains $8$ protons and $9$ neutrons. It is known that the atomic number of an atom is equal to the number of protons. Therefore, atomic number of the given atom is $8$.

The formula to calculate mass number is,

$\text{Mass}\text{number}=\text{Atomic}\text{number}+\text{number}\text{of}\text{neutrons}$

Substitute the values in the above equation.

$\begin{array}{rll}\text{Mass}\text{number}& =& \text{Atomic}\text{number}+\text{number}\text{of}\text{neutrons}\\ & =& 8+\text{9}\\ & =& \text{17}\end{array}$

The representation of an atom is as follows.

${}_{\text{x}}^{\text{y}}\text{A}$

Where,

• $\text{x}$ represents the atomic number of the atom $\text{A}$.

• $\text{y}$ represents the mass number of the atom $\text{A}$.

The atom with atomic number $8$ is oxygen and it has atomic symbol $\text{O}$. The mass number calculated for it, is $17$. Thus, the symbol for oxygen can be written as given below.

${}_{\text{8}}^{\text{17}}\text{O}$

Conclusion

The mass number and atomic number for an atom containing nucleus made up of $8$ protons and $9$ neutrons are calculated as $17$ and $8$ respectively. The symbol is represented as ${}_{\text{8}}^{\text{17}}\text{O}$.

Interpretation Introduction

(c)

Interpretation:

The mass number and atomic number for atom containing nucleus made up of $20$ protons and $25$ neutrons are to be calculated and the symbol for an atom is to be stated.

Concept introduction:

The atomic number of an atom is equal to the number of protons in an atom. Mass number of an atom can be calculated by taking the sum of atomic number and number of neutrons. The general isotopic symbol for an atom is represented as given below.

${}_{\text{x}}^{\text{y}}\text{A}$

Answer to Problem 2.19E

The mass number and atomic number for an atom containing nucleus made up of $20$ protons and $25$ neutrons are $45$ and $20$ respectively. The symbol is represented as ${}_{\text{20}}^{\text{45}}\text{Ca}$.

Explanation of Solution

The given atom contains $20$ protons and $25$ neutrons. It is known that the atomic number of an atom is equal to the number of protons. Therefore, atomic number of the given atom is $20$.

The formula to calculate mass number is,

$\text{Mass}\text{number}=\text{Atomic}\text{number}+\text{number}\text{of}\text{neutrons}$

Substitute the values in the above equation as given below.

$\begin{array}{rll}\text{Mass}\text{number}& =& \text{Atomic}\text{number}+\text{number}\text{of}\text{neutrons}\\ & =& 20+\text{25}\\ & =& 45\end{array}$

The representation of an atom is as follows.

${}_{\text{x}}^{\text{y}}\text{A}$

Where,

• $\text{x}$ represents the atomic number of the atom $\text{A}$.

• $\text{y}$ represents the mass number of the atom $\text{A}$.

The atom with atomic number $20$ is calcium and it has atomic symbol $\text{Ca}$. The mass number calculated for it, is $45$. Thus, the symbol for calcium can be written as given below.

${}_{\text{20}}^{\text{45}}\text{Ca}$

Conclusion

The mass number and atomic number for atom containing nucleus made up of $20$ protons and $25$ neutrons are calculated as $45$ and $20$ respectively. The symbol is represented as ${}_{\text{20}}^{\text{45}}\text{Ca}$.

Interpretation Introduction

(d)

Interpretation:

The mass number and atomic number for atom containing nucleus made up of $52$ protons and $78$ neutrons are to be calculated and the symbol for the atom is to be stated.

Concept introduction:

The atomic number of an atom is equal to the number of protons in an atom. Mass number of an atom can be calculated by taking the sum of atomic number and number of neutrons. The isotopic symbol for an atom is represented as given below.

${}_{\text{x}}^{\text{y}}\text{A}$

Answer to Problem 2.19E

The mass number and atomic number for an atom containing nucleus made up of $52$ protons and $78$ neutrons are $130$ and $52$ respectively. The symbol is represented as ${}_{\text{52}}^{\text{130}}\text{Te}$.

Explanation of Solution

The given atom contains $52$ protons and $78$ neutrons. It is known that the atomic number of an atom is equal to the number of protons. Therefore, atomic number of the given atom is $52$.

The formula to calculate mass number is,

$\text{Mass}\text{number}=\text{Atomic}\text{number}+\text{number}\text{of}\text{neutrons}$

Substitute the values in the above equation.

$\begin{array}{rll}\text{Mass}\text{number}& =& \text{Atomic}\text{number}+\text{number}\text{of}\text{neutrons}\\ & =& 52+78\\ & =& 130\end{array}$

The representation of an atom is as follows.

${}_{\text{x}}^{\text{y}}\text{A}$

Where,

• $\text{x}$ represents the atomic number of the atom $\text{A}$.

• $\text{y}$ represents the mass number of the atom $\text{A}$.

The atom with atomic number $52$ is tellurium and it has atomic symbol $\text{Te}$. The mass number calculated for it, is $130$. Thus, the symbol for tellurium can be written as given below.

${}_{\text{52}}^{\text{130}}\text{Te}$

Conclusion

The mass number and atomic number for an atom containing nucleus made up of $52$ protons and $78$ neutrons are calculated as $130$ and $52$ respectively. The symbol is represented as ${}_{\text{52}}^{\text{130}}\text{Te}$.