Chapter 2, Problem 12Q

Give the symbol showing the atomic number and the mass number for the isotope that has:

1. a. 9 protons and 10 neutrons (used in nuclear medicine).
2. b. 26 protons and 30 neutrons (the most stable isotope of this element).
3. c. 86 protons and 136 neutrons (the radioactive gas found in some homes).

Interpretation Introduction

Interpretation:

The symbol has to be given for the isotope which has 9 protons and 10 neutrons.

Concept Introduction:

According to modern periodic table, both the physical and chemical properties of elements depend on their atomic number in a periodic way.

Modern periodic table contains groups and periods where the elements same number of outer electrons comes under same group and elements having same number of electron shells are in same period.

Figure 1

In a periodic table, an element is represented as shown below,

Atomic number is equal to the number of proton ($N_P$), which also equal to the number of electrons ($N_e$).

The atomic mass can be calculated using the formula,

$Atomicmass=Numberofprotons\left(N_P\right)+Numberofneutrons\left(N_n\right)$

$Numberofneutrons\left(N_n\right)=Atomicmass(A)-Numberofprotons\left(N_P\right)$

Isotopes are species which have the same number of protons and different mass number.

Examples: ${}_1{H}^1,{}_1{H}^{2}and{}_1{H}^3$

Explanation of Solution

The given isotope has 9 protons and 10 neutrons. Proton number helps to find the isotope’s symbol.

The element which has nine protons is Flourine and its symbol is F.

Mass number of the isotope can be determined by using the equation,

$\begin{array}{c}Atomicmass(A)=Numberofprotons\left(N_P\right)+Numberofneutrons\left(N_n\right)\\ =9+10\\ =19\end{array}$

Thus, the isotope can be represented using its symbol as follows,

${}_9{F}^{19}$

Interpretation Introduction

Interpretation:

The symbol has to be given for the isotope which has 26 protons and 30 neutrons.

Concept Introduction:

According to modern periodic table, both the physical and chemical properties of elements depend on their atomic number in a periodic way.

Modern periodic table contains groups and periods where the elements same number of outer electrons comes under same group and elements having same number of electron shells are in same period.

Figure 1

In a periodic table, an element is represented as shown below,

Atomic number is equal to the number of proton ($N_P$), which also equal to the number of electrons ($N_e$).

The atomic mass can be calculated using the formula,

$Atomicmass=Numberofprotons\left(N_P\right)+Numberofneutrons\left(N_n\right)$

$Numberofneutrons\left(N_n\right)=Atomicmass(A)-Numberofprotons\left(N_P\right)$

Isotopes are species which have the same number of protons and different mass number.

Examples: ${}_1{H}^1,{}_1{H}^{2}and{}_1{H}^3$

Explanation of Solution

The given isotope has 26 protons and 30 neutrons. Proton number helps to find the isotope’s symbol.

The element which has 26 protons is Iron and its symbol is Fe.

Mass number of the isotope can be determined by using the equation,

$\begin{array}{c}Atomicmass(A)=Numberofprotons\left(N_P\right)+Numberofneutrons\left(N_n\right)\\ =26+30\\ =56\end{array}$

Thus, the isotope can be represented using its symbol as follows,

${}_{26}F{e}^{56}$

Interpretation Introduction

Interpretation:

The symbol has to be given for the isotope which has 86 protons and 136 neutrons.

Concept Introduction:

According to modern periodic table, both the physical and chemical properties of elements depend on their atomic number in a periodic way.

Modern periodic table contains groups and periods where the elements same number of outer electrons comes under same group and elements having same number of electron shells are in same period.

Figure 1

In a periodic table, an element is represented as shown below,

Atomic number is equal to the number of proton ($N_P$), which also equal to the number of electrons ($N_e$).

The atomic mass can be calculated using the formula,

$Atomicmass=Numberofprotons\left(N_P\right)+Numberofneutrons\left(N_n\right)$

$Numberofneutrons\left(N_n\right)=Atomicmass(A)-Numberofprotons\left(N_P\right)$

Isotopes are species which have the same number of protons and different mass number.

Examples: ${}_1{H}^1,{}_1{H}^{2}and{}_1{H}^3$

Explanation of Solution

The given isotope has 86 protons and 136 neutrons. Proton number helps to find the isotope’s symbol.

The element which has 86 protons is Radon and its symbol is Rn.

Mass number of the isotope can be determined by using the equation,

$\begin{array}{c}Atomicmass(A)=Numberofprotons\left(N_P\right)+Numberofneutrons\left(N_n\right)\\ =86+136\\ =222\end{array}$

Thus, the isotope can be represented using its symbol as follows,

${}_{86}R{n}^{222}$