Question

(a) Give the names and chemical symbols for the three isotopes of hydrogen. (b) List the isotopes in order of decreasing natural abundance.

Short answer

The three isotopes of hydrogen and their chemical symbols are: 1. Protium (\(_1^1 H\)) - one proton and no neutrons 2. Deuterium (\(_1^2 H\)) - one proton and one neutron 3. Tritium (\(_1^3 H\)) - one proton and two neutrons. The order of decreasing natural abundance of hydrogen isotopes is: Protium (over 99.98%), Deuterium (approximately 0.0156%), and Tritium (trace amounts).

Step-by-step solution

(Identify the isotopes of hydrogen and their chemical symbols)

The three isotopes of hydrogen and their chemical symbols are as follows: 1. Protium (\(_1^1 H\)) - This is the most common hydrogen isotope with one proton and no neutrons. 2. Deuterium (\(_1^2 H\)) - This hydrogen isotope includes one proton and one neutron. 3. Tritium (\(_1^3 H\)) - This hydrogen isotope consists of one proton and two neutrons.

(List the isotopes in order of decreasing natural abundance)

To list the hydrogen isotopes in order of decreasing natural abundance, we have to know the relative abundance of each isotope: 1. Protium - This isotope is the most abundant hydrogen isotope. Over 99.98% of all hydrogen atoms are protium. 2. Deuterium - This isotope is rarer than protium. It constitutes approximately 0.0156% of all hydrogen atoms. 3. Tritium - This isotope is the least abundant hydrogen isotope, as it is radioactive and has a half-life of 12.3 years. It occurs naturally in trace amounts due to cosmic radiation interactions with atmospheric gases. Thus, the order of decreasing natural abundance of hydrogen isotopes is: Protium, Deuterium, and Tritium, respectively.

Key concepts

Protium

Protium is the most prevalent isotope of hydrogen, making up over 99.98% of all hydrogen atoms found on Earth. This abundance is mainly due to the simplicity of its atomic structure. Protium consists of just one proton and does not have any neutrons in its nucleus. This makes it distinct among hydrogen isotopes, as others have additional neutrons. You can represent Protium chemically with the symbol \(^1_1 H\).

Due to its widespread presence and simple structure, Protium plays a significant role in various chemical processes. It is the form of hydrogen commonly found in water molecules when bonded with oxygen. Additionally, Protium is utilized in hydrogen fuel cells, a technology considered pivotal for sustainable energy solutions. Understanding this isotope is crucial as it serves as a building block for more complex hydrogen compounds.

Deuterium

Deuterium is a rare but stable isotope of hydrogen. It comprises one proton and one neutron in its nucleus, giving it a greater atomic weight than Protium. Represented by the chemical symbol \(^2_1 H\), Deuterium accounts for approximately 0.0156% of all hydrogen atoms in nature.

Despite its low abundance, Deuterium has significant industrial and scientific applications. It is used in nuclear reactors as a moderator to slow down neutrons during nuclear fission reactions, thanks to its ability to absorb neutrons. In the field of chemistry and biochemistry, deuterium-labeled compounds are employed to trace chemical reactions and pathways. These characteristics make Deuterium an important isotope to understand within the context of both natural and man-made processes.

Tritium

Tritium is the least abundant hydrogen isotope, and unlike Protium and Deuterium, it is radioactive. Tritium has one proton and two neutrons in its nucleus, which contributes to its instability. It is denoted by the symbol \(^3_1 H\).

The radioactivity of Tritium means it has a limited natural presence, occurring in trace amounts as a result of cosmic ray interactions with the atmosphere. Tritium has a half-life of approximately 12.3 years, after which it decays into a helium-3 nucleus.

• Tritium is used in self-luminous devices, such as exit signs and watch dials, where it provides a long-lasting glow without the need for an external power source.
• In nuclear fusion research, Tritium is a potential fuel source, offering the promise of cleaner and more sustainable energy production over conventional nuclear reactions.

Understanding Tritium's properties is essential in fields that utilize its unique characteristics for both practical and experimental purposes.