Chapter 4, Problem 51A

Interpretation Introduction

Interpretation : The mass number for the given element is to be calculated.

Concept Introduction : The mass number is the sum of the protons and neutrons in an atom.

Answer to Problem 51A

The mass number of the element is 19.

Explanation of Solution

Given information:

The atomic number is 9.

The number of neutrons is 10.

The mass number gives the protons and neutrons count of an atom while the atomic number gives only the protons count.

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

To calculate the mass number, substitute the values in the above formula:

  $\begin{array}{c}\text{Mass}\text{number}\text{=}\text{Atomic}\text{number}\text{+}\text{Number}\text{of}\text{neutrons}\\ \text{= 9 + 10}\\ \text{=19}\end{array}$

The mass number of the element is 19.

Interpretation Introduction

Interpretation : The number of protons for the given element is to be calculated.

Concept Introduction : Protons are positively charged subatomic particles present in the nucleus discovered by Eugen Goldstein.

Answer to Problem 51A

The number of protons in the element of atomic number 9 is 9.

Explanation of Solution

Given information:

The atomic number is 9.

Protons are positively charged subatomic particles present in the nucleus discovered by Eugen Goldstein.

The number of protons in the nucleus of an element's atom is known as the element's atomic number. An element is identified by its atomic number.

As the atomic number is 9, the neutral atom has 9 protons.

Interpretation Introduction

Interpretation : The atomic number for the given element is to be calculated.

Concept Introduction : The number of protons in the nucleus of an element's atom is known as the element's atomic number.

Answer to Problem 51A

The atomic number for the element is 14.

Explanation of Solution

Given information :

The number of protons is 14.

The number of protons in the nucleus of an element's atom is known as the element's atomic number.

As the number of protons is 14, the atomic number will also be 14.

Interpretation Introduction

Interpretation : The mass number for the given element is to be calculated.

Concept Introduction : The mass number is the sum of the protons and neutrons in an atom.

Answer to Problem 51A

The mass number of the element is 29.

Explanation of Solution

Given information:

The number of protons is 14.

The number of neutrons is 15.

The mass number gives the protons and neutrons count of an atom while the atomic number gives only the protons count.

  $\text{Mass}\text{number}\text{=}\text{Number of protons}\text{+}\text{Number}\text{of}\text{neutrons}$

To calculate the mass number, substitute the values in the above formula:

  $\begin{array}{c}\text{Mass}\text{number}\text{=}\text{Number of protons}\text{+}\text{Number}\text{of}\text{neutrons}\\ \text{= 15 + 15}\\ \text{= 29}\end{array}$

The mass number of the element is 29.

Interpretation Introduction

Interpretation : The atomic number of the element is to be calculated.

Concept Introduction : The number of protons in the nucleus of an element's atom is known as the element's atomic number.

Answer to Problem 51A

The atomic number of the element is 22.

Explanation of Solution

Given information :

The mass number is 47.

The number of neutrons is 25.

The number of protons in the nucleus of an element's atom is known as the element's atomic number.

As only the mass number and neutrons of the element are known, the formula for atomic number is given as

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

To calculate the atomic number, substitute the values in above formula:

  $\begin{array}{c}\text{Atomic number =}\text{Mass}\text{number}-\text{Number}\text{of}\text{neutrons}\\ \text{= 47 }-\text{ 25}\\ \text{= 22}\end{array}$

The atomic number of the element is 22.

Interpretation Introduction

Interpretation : The number of protons for the given element is to be calculated.

Concept Introduction : Protons are positively charged subatomic particles present in the nucleus discovered by Eugen Goldstein.

Answer to Problem 51A

The number of protons is 22.

Explanation of Solution

Given information :

The mass number is 47.

The number of neutrons is 25.

Protons are positively charged subatomic particles present in the nucleus discovered by Eugen Goldstein.

As only the mass number and neutrons of the element are known, the formula for number of protons is given as

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

To calculate the number of protons, substitute the values in the above formula:

  $\begin{array}{c}\text{Number of protons =}\text{Mass}\text{number}-\text{Number}\text{of}\text{neutrons}\\ \text{= 47 }-\text{ 25}\\ \text{= 22}\end{array}$

The number of protons of the element is 22.

Interpretation Introduction

Interpretation : The atomic number for the given element is to be calculated.

Concept Introduction : The number of protons in the nucleus of an element's atom is known as the element's atomic number.

Answer to Problem 51A

The atomic number for the element is 25.

Explanation of Solution

Given information :

The number of protons is 25.

The number of protons in the nucleus of an element's atom is known as the element's atomic number.

As the number of protons is 25, the atomic number will also be 25.

Interpretation Introduction

Interpretation : The number of neutrons for the given element is to be calculated.

Concept Introduction : Neutrons are neutrally charged subatomic particles present in the nucleus discovered by James Chadwick.

Answer to Problem 51A

The number of neutrons of the element is 30.

Explanation of Solution

Given information :

The mass number is 55.

The number of protons is 25.

Neutrons are neutrally charged subatomic particles present in the nucleus discovered by James Chadwick.

The formula for the number of neutrons is given as

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

To calculate the number of neutrons, substitute the values in the above formula:

  $\begin{array}{c}\text{Number of neutrons = Mass number }-\text{Number of protons}\\ \text{=}\text{55}-25\\ =30\end{array}$

So, the number of neutrons is 30.