Problem 135 - A Complete Resource Book in Chemistry for JEE Main

Question

Match the lists I and II and pick the correct matching from the codes given below, Column-I (a) Isotope (b) Isobar (c) Isotone (d) Isosters (e) Isodiaphers Column-II (p) \({ }_{88} \mathrm{Ra}^{228}\) and \({ }_{89} \mathrm{Ac}^{228}\) (q) \({ }_{18} \mathrm{Ar}^{39}\) and \({ }_{19} \mathrm{~K}^{40}\) (r) \({ }_{1} \mathrm{H}^{2}\) and \({ }_{1} \mathrm{H}^{3}\) (s) \({ }_{92} \mathrm{U}^{235}\) and \(_{90}^{\mathrm{Th} 231}\) (t) \(\mathrm{CO}_{2}\) and \(\mathrm{N}_{2} \mathrm{O}\)

Step-by-Step Solution

Answer

The correct match is: (a) - (r), (b) - (p), (c) - (q), (d) - (t), (e) - (s).

Step 1: Define Isotope

Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons, hence different mass numbers. In this context: - Column I: (a) Isotope - Column II: Matches with (r) ext{${ }_{1} ext{H}^{2}$ and ${ }_{1} ext{H}^{3}$} Both have the same atomic number, which is 1, representing the Hydrogen element, but different mass numbers (2 and 3).

Step 2: Define Isobar

Isobars are atoms of different elements that have the same mass number but different atomic numbers. In this context: - Column I: (b) Isobar - Column II: Matches with (p) ext{${ }_{88} ext{Ra}^{228}$ and ${ }_{89} ext{Ac}^{228}$} Both have the same mass number, 228, but different atomic numbers, 88 and 89, respectively.

Step 3: Define Isotone

Isotones are atoms that have the same number of neutrons but different numbers of protons. In this context: - Column I: (c) Isotone - Column II: Matches with (q) ext{${ }_{18} ext{Ar}^{39}$ and ${ }_{19} ext{~K}^{40}$} Both elements have 21 neutrons (protons are 18 and 19, while mass numbers are 39 and 40).

Step 4: Define Isoster

Isosters are molecules or ions of different elements that have the same number of atoms and a similar structure or count of valence electrons. In this context: - Column I: (d) Isosters - Column II: Matches with (t) ext{CO}_{2} ext{and} ext{N}_{2} ext{O} Both compounds have the same total number of atoms, and their electron cloud shapes are similar.

Step 5: Define Isodiapher

Isodiaphers are atoms with the difference in their numbers of neutrons and protons being the same. In this context: - Column I: (e) Isodiapher - Column II: Matches with (s) ext{${ }_{92} ext{U}^{235}$ and $_{90}^{ ext{Th} 231}$} Both have a neutron-proton difference of 143.

Key Concepts

Isobars

Isobars are fascinating entities in the world of atomic science. They are atoms belonging to different elements but sharing one crucial aspect: their mass number. Mass number is the sum of protons and neutrons within an atom’s nucleus. Despite having the same mass number, isobars differ in their atomic numbers, implying they belong to different elements.

• Isobars Example: Consider \({ }_{88} \text{Ra}^{228}\) and \({ }_{89} \text{Ac}^{228}\). Both of these atoms have a mass number of 228, although they have different atomic numbers, 88 for Ra and 89 for Ac.
• Significance: Isobars highlight how different elements can have the same total nucleon count, which opens doors to unique interactions in nuclear physics and chemistry.

Exploring isobars reveals fascinating dynamics between elements and provides crucial insights into the subtleties of atomic structure.

Isotones

Isotones broaden our understanding by focusing on neutrons. These are atoms of different elements that have the same number of neutrons but differ in the number of protons and atomic mass. By concentrating on the neutron count, isotones offer another avenue to compare and contrast atoms.

• Isotones Example: \({ }_{18} \text{Ar}^{39}\) and \({ }_{19} \text{K}^{40}\) both have 21 neutrons. Though they are different elements, Argon having 18 protons and Potassium with 19.
• Functionality: Isotones allow scientists to study nuclear properties, such as nuclear stability and reactions that involve neutron interactions.

They are instrumental in many scientific fields, including the study of the nuclear shell model and neutron capture processes.

Isosters

Isosters step outside the single element focus and look at molecules or ions with the same number of atoms and a similar size or shape, often determined by the valence electrons. This structural kinship offers insights into how different compounds might exhibit similar behaviors in chemical reactions.

• Isosters Example: \( ext{CO}_{2}\) and \( ext{N}_{2} ext{O}\). Despite having different compositions, they have a similar shape and number of total atoms, making them structural relatives.
• Utilities: Isosters are crucial for understanding reactivity and molecular interactions in various chemical contexts, including drug design where subtle changes can significantly impact efficacy and interaction.

This concept extends the conversation into molecular geometry and chemical properties, providing a broader perspective on molecular science.

Isodiaphers

Isodiaphers are a less common but insightful concept focusing on the balance between protons and neutrons. Atoms are considered isodiaphers if they have the same difference between their numbers of neutrons and protons.

• Isodiaphers Example: \({ }_{92} \text{U}^{235}\) and \(_{90}^{ ext{Th} 231}\) both exhibit a neutron-proton difference of 143.
• Implications: Examining isodiaphers can help in understanding nuclear stability and predicting the type of decay an unstable isotope might undergo.

Isodiaphers provide a unique lens through which to examine atomic characteristics and behaviors, especially valuable in nuclear chemistry and related fields.