Problem 52 - 43 Years JEE ADVANCED (1978-2020) + JEE MAIN Chapterwise & Topicwise Solved Papers Chemistry

Question

The sum of the number of neutrons and proton in the isotope of hydrogen is : (a) 6 (b) 2 (c) 4 (d) 3

Step-by-Step Solution

Answer

(d) 3

Step 1: Understanding Isotopes of Hydrogen

Hydrogen has three isotopes: Protium, Deuterium, and Tritium. Protium has 1 proton and 0 neutrons, Deuterium has 1 proton and 1 neutron, and Tritium has 1 proton and 2 neutrons.

Step 2: Calculating Neutrons and Protons

For each isotope of hydrogen, calculate the sum of the number of neutrons and protons: - Protium: 1 proton + 0 neutrons = 1 - Deuterium: 1 proton + 1 neutron = 2 - Tritium: 1 proton + 2 neutrons = 3

Step 3: Determine the Correct Option

Compare the calculated sums with the given options: - Option (a) 6: None of the isotopes have this sum. - Option (b) 2: Matches with Deuterium. - Option (c) 4: None of the isotopes have this sum. - Option (d) 3: Matches with Tritium.

Key Concepts

Proton

Protons are subatomic particles found in the nucleus of an atom. They carry a positive charge and play a crucial role in defining the identity of an element. In hydrogen isotopes, each atom contains exactly one proton, which is the defining feature for these isotopes.
For hydrogen and its isotopes:

• The proton is key because it determines that the atom is a hydrogen, no matter how many neutrons are present.
• All hydrogen isotopes, including protium, deuterium, and tritium, have one proton.

Understanding protons helps us identify different isotopes based on their proton and neutron numbers. They are essential for balancing atomic structure and understanding chemical reactions.

Neutron

Neutrons are neutral particles found in the atomic nucleus alongside protons. Unlike protons, neutrons carry no charge, but they have a similar mass. The number of neutrons in an isotope affects the isotope's mass and stability.
For hydrogen isotopes:

• Protium has no neutrons, making it the lightest hydrogen isotope.
• Deuterium has one neutron, doubling the mass compared to protium.
• Tritium contains two neutrons, giving it the most mass and rendering it less stable.

Neutrons are crucial in maintaining the stability of an atom, as they contribute to the strong forces that keep the nucleus intact.

Tritium

Tritium is the heaviest naturally occurring isotope of hydrogen. It contains one proton and two neutrons. Tritium is radioactive and less stable compared to other isotopes.
Characteristics of tritium:

• It has a half-life of about 12.32 years, slowly decaying into helium-3 through beta decay.
• Tritium is used in thermonuclear reactions and as a tracer in biochemical research due to its radioactive nature.
• It contributes only minimally to the hydrogen present in nature because of its rarity and radioactivity.

Tritium's unique properties make it interesting for scientific research and nuclear applications.

Deuterium

Deuterium is an isotope of hydrogen, known as heavy hydrogen. It consists of one proton and one neutron in its nucleus, providing unique physical properties.
Key features of deuterium:

• Deuterium has roughly double the mass of the most common hydrogen isotope, protium due to the presence of the neutron.
• It is non-radioactive and stable, making it safe for various applications.
• Commonly used in heavy water, deuterium serves as a moderator in nuclear reactors and in studies of reaction mechanisms due to its stable nature.

Its heavier nature makes it valuable across scientific and industrial domains.

Protium

Protium is the most abundant and simplest isotope of hydrogen. It consists of one proton and no neutrons, making it the lightest and most common form of hydrogen.
Characteristics of protium:

• It accounts for nearly all hydrogen found on Earth.
• Due to having no neutrons, protium has a mass number of 1.
• Widely used in chemical reactions and studies due to its simplicity and abundance.

Protium's simplicity is foundational for understanding hydrogen's role in chemical and physical processes.