Chapter 2, Problem 2.53AP

(a)

Interpretation Introduction

Interpretation:

The atomic number, number of protons, number of neutrons, and number of electrons of carbon 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 element symbol is $\text{C}\text{.}$

The mass number is $12.$

The atomic number of carbon is $6.$

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

Thus, the number of protons in the atom is $6.$

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

Thus, the number of electrons in the atom is $6.$

The number of neutrons can be calculated as,

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

  $\begin{array}{l}\text{Number}\text{of}\text{neutrons=A-Number}\text{of}\text{protons}\\ \text{Number}\text{of}\text{neutrons=12-6}\\ \text{Number}\text{of}\text{neutrons=6}\end{array}$

The number of neutrons in an atom is $6.$

(b)

Interpretation Introduction

Interpretation:

The element symbol, atomic number, number of protons and the number of neutrons for the given mass number 35 and the number of electrons 15 has to be calculated.

Concept Introduction:

Refer to part (a).

Explanation of Solution

Given,

The number of electrons is $15.$

The mass number is $31.$

  $\text{Atomic number of an element=Number of electrons}$

The atomic number of carbon is $15.$

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

Thus, the number of protons in the atom is $15.$

The number of neutrons can be calculated as,

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

  $\begin{array}{l}\text{Number}\text{of}\text{neutrons=A-Number}\text{of}\text{protons}\\ \text{Number}\text{of}\text{neutrons=31-15}\\ \text{Number}\text{of}\text{neutrons=16}\end{array}$

The number of neutrons in an atom is $16.$

An element with atomic number $\text{15}$ is phosphorous.

(c)

Interpretation Introduction

Interpretation:

The element symbol, atomic number, number of protons and the mass number for the given number of neutrons 35 and the number of electrons 30 has to be calculated.

Concept Introduction:

Refer to part (a).

Explanation of Solution

Given,

The number of electrons is $30.$

The number of neutrons is $35.$

  $\text{Atomic number of an element=Number of electrons}$

The atomic number of carbon is $30.$

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

Thus, the number of protons in the atom is $30.$

The mass number can be calculated as,

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

  $\begin{array}{l}\text{A=30+}\text{35}\\ \text{A=65}\end{array}$

The mass number is $65.$

An element with atomic number $30$ is Zinc.

(d)

Interpretation Introduction

Interpretation:

The atomic number, number of protons, number of neutrons, and number of electrons of Magnesium has to be given.

Concept introduction;

Refer to part (a).

Explanation of Solution

Given,

The element symbol is $\text{Mg}\text{.}$

The mass number is $24.$

The atomic number of magnesium is $12.$

  $\text{Atomic number of an element=Number of electrons}$

Thus, the number of protons in the atom is $12.$

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

Thus, the number of electrons in the atom is $12.$

The number of neutrons can be calculated as,

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

  $\begin{array}{l}\text{Number}\text{of}\text{neutrons=A-Number}\text{of}\text{protons}\\ \text{Number}\text{of}\text{neutrons=24-12}\\ \text{Number}\text{of}\text{neutrons=12}\end{array}$

The number of neutrons in an atom is $12.$