Chapter U1.14, Problem 6E

Interpretation Introduction

(a)

Interpretation:

Isotope name and isotope symbol of three isotopes with equal number of neutrons and protons are to be found using the isotope graph.

Concept introduction:

The atoms with different mass numbers but same atomic number are known as isotopes. Here, mass number is sum of protons and neutrons present in the nucleus. The number of protons is same for two isotopes thus, the main difference is in the number of neutrons.

Answer to Problem 6E

The following table shows three isotopes with equal number of protons and neutrons.

S. no	Isotope name	Isotope symbol
1	Neon - 20	${}_{10}^{20}\text{Ne}$
2	Phosphorus - 30	${}_{15}^{30}\text{P}$
3	Calcium - 40	${}_{20}^{40}\text{Ca}$

Explanation of Solution

Isotopes which fall on the diagonal line have same number of protons and neutrons.

1. Neon-20 - Neon has 10 protons. From the graph we can see an isotope of neon which has 10 protons and 10 neutrons. This isotope lies on the diagonal line.
2. Phosphorus - 30 - From the graph we can see an isotope of phosphorus which has 15 protons and 15 neutrons. This isotope lies on the diagonal line.
3. Calcium - 40 - From the graph we can see an isotope of calcium which has 20 protons and 20 neutrons. This isotope lies on the diagonal line.

Interpretation Introduction

(b)

Interpretation:

Isotope name and isotope symbol of two isotopes with same number of protons are to be found using the isotope graph.

Concept introduction:

The atoms with different mass numbers but same atomic number are known as isotopes. Here, mass number is sum of protons and neutrons present in the nucleus. The number of protons is same for two isotopes thus, the main difference is in the number of neutrons.

Answer to Problem 6E

The following table shows two isotopes with same number of protons.

S. no	Isotope name	Isotope symbol
1	Boron-10	${}_5^{10}\text{B}$
2	Boron - 11	${}_5^{11}\text{B}$

Explanation of Solution

Isotopes of the same element have same number of protons. Boron-10 and boron-1; both have 5 protons. From the graph one can see two isotopes of boron which have5 protons but 5 and 6 neutrons respectively.

(c)

Interpretation Introduction

Interpretation:

Isotope name and isotope symbol of two isotopes with same number of neutrons are to be found using the isotope graph.

Concept introduction:

The atoms with different mass numbers but same atomic number are known as isotopes. Here, mass number is sum of protons and neutrons present in the nucleus. The number of protons is same for two isotopes thus, the main difference is in the number of neutrons.

Answer to Problem 6E

The following table shows two isotopes with same number of neutrons.

S. no	Isotope name	Isotope symbol
1	Phosphorus - 35	${}_{15}^{35}\text{P}$
2	Calcium - 40	${}_{\text{20}}^{\text{40}}\text{Ca}$

Explanation of Solution

Isotopes of the different elements may have same number of neutrons but isotopes of same element have different number of neutrons.

From the graph, one can see an isotope of phosphorus having 20 neutrons and an isotope of calcium having 20 neutrons. Both have different number of protons.

(d)

Interpretation Introduction

Interpretation:

Isotope name and isotope symbol of two isotopes with same atomic mass units are to be found using the isotope graph.

Concept introduction:

The atoms with different mass numbers but same atomic number are known as isotopes. Here, mass number is sum of protons and neutrons present in the nucleus. The number of protons is same for two isotopes thus, the main difference is in the number of neutrons.

Answer to Problem 6E

The following table shows two isotopes with same atomic mass units.

S. no	Isotope name	Isotope symbol
1	Phosphorus - 40	${}_{15}^{40}\text{P}$
2	Calcium - 40	${}_{\text{20}}^{\text{40}}\text{Ca}$

Explanation of Solution

Isotopes of the different elements may have atomic mass but isotopes of same element have different atomic mass.

From the graph we can see an isotope of phosphorus having 25 neutrons and 15 protons. so atomic mass of phosphorus is 40 units.

An isotope of calcium has 20 neutrons and 20 protons. Atomic mass of calcium is 40 units.

Hence, phosphorus - 40 and calcium - 40 have same atomic mass units.