Chapter 2, Problem 2.54AP

(a)

Interpretation Introduction

Interpretation:

The element symbol, element name, number of protons, number of electrons and the number of neutrons of an element with atomic number 10 has to be given.

Concept introduction;

Atomic number (Z):

Atomic number of an element is the number of protons or the number of electrons found in the nucleus of every atom of that element.

Mass number (A):

Mass number of an element is defined as the total number of protons and neutrons in an atom.

Protons:

A proton is one of three main particles that make up the atom.  Protons are a tiny, dense region at the center of the atom.  Protons have a positive electrical charge of $+1$ and a mass of 1 atomic mass which is $\text{1}{\text{.62×10}}^{\text{-27}}$ kilograms.

Neutrons:

Atoms of all elements except for most atoms of hydrogen have neutrons in their nucleus. Unlike protons and electrons, which are electrically charged, neutrons have no charge they are electrically neutral.

Electrons:

Electrons have an electric charge of $\text{-1}$, which is equal but opposite to the charge of a proton, which have an electric charge of $\text{+1}\text{.}$  All atoms have the same number of electrons as protons, so the positive and negative charges cancel out making atoms electrically neutral.

Explanation of Solution

Given,

The atomic number is $10.$

The mass number is $20.$

An element with atomic number $\text{10}$ is Neon.  Neon is the chemical element with chemical symbol $\text{Ne}\text{.}$

  $\text{Atomic number of an element=The number of protons}$

Thus, the number of protons in the atom is $10.$

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

Thus, the number of electrons in the atom is $10.$

The number of neutrons can be calculated as,

  $\text{A=Number}\text{of}\text{protons}\text{+}\text{Number}\text{of}\text{neutrons}$

  $\begin{array}{l}\text{Number}\text{of}\text{neutrons=A-Number}\text{of}\text{protons}\\ \text{Number}\text{of}\text{neutrons=20-10}\\ \text{Number}\text{of}\text{neutrons=10}\end{array}$

The number of neutrons in an atom is $10.$

(b)

Interpretation Introduction

Interpretation:

The element symbol, element name, number of protons, number of electrons and the number of neutrons of an element with atomic number 13 has to be given.

Concept Introduction:

Refer to part (a).

Explanation of Solution

Given,

The atomic number is $13.$

The mass number is $27.$

An element with atomic number $13$ is Aluminium.  Aluminium is the chemical element with chemical symbol $\text{Al}\text{.}$

  $\text{Atomic number of an element=The number of protons}$

Thus, the number of protons in the atom is $13.$

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

Thus, the number of electrons in the atom is $13.$

The number of neutrons can be calculated as,

  $\text{A=Number}\text{of}\text{protons}\text{+}\text{Number}\text{of}\text{neutrons}$

  $\begin{array}{l}\text{Number}\text{of}\text{neutrons=A-Number}\text{of}\text{protons}\\ \text{Number}\text{of}\text{neutrons=27-13}\\ \text{Number}\text{of}\text{neutrons=14}\end{array}$

The number of neutrons in an atom is $14.$

(c)

Interpretation Introduction

Interpretation:

The element symbol, element name, number of protons, number of electrons and the number of neutrons of an element with atomic number 38 has to be given.

Concept Introduction:

Refer to part (a).

Explanation of Solution

Given,

The atomic number is $38.$

The mass number is $88.$

An element with atomic number $38$ is Strontium.  Strontium is the chemical element with chemical symbol $\text{Sr}\text{.}$

  $\text{Atomic number of an element=The number of protons}$

Thus, the number of protons in the atom is $38.$

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

Thus, the number of electrons in the atom is $38.$

The number of neutrons can be calculated as,

  $\text{A=Number}\text{of}\text{protons}\text{+}\text{Number}\text{of}\text{neutrons}$

  $\begin{array}{l}\text{Number}\text{of}\text{neutrons=A-Number}\text{of}\text{protons}\\ \text{Number}\text{of}\text{neutrons=88-38}\\ \text{Number}\text{of}\text{neutrons=50}\end{array}$

The number of neutrons in an atom is $50.$

(d)

Interpretation Introduction

Interpretation:

The element symbol, element name, number of protons, number of electrons and the number of neutrons of an element with atomic number 55 has to be given.

Concept Introduction:

Refer to part (a).

Explanation of Solution

Given,

The atomic number is $55.$

The mass number is $133.$

An element with atomic number $55$ is Cesium.  Cesium is the chemical element with chemical symbol $\text{Cs}\text{.}$

  $\text{Atomic number of an element=The number of protons}$

Thus, the number of protons in the atom is $55.$

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

Thus, the number of electrons in the atom is $55.$

The number of neutrons can be calculated as,

  $\text{A=Number}\text{of}\text{protons}\text{+}\text{Number}\text{of}\text{neutrons}$

  $\begin{array}{l}\text{Number}\text{of}\text{neutrons=A-Number}\text{of}\text{protons}\\ \text{Number}\text{of}\text{neutrons=133-55}\\ \text{Number}\text{of}\text{neutrons=78}\end{array}$

The number of neutrons in an atom is $78.$