Question

Tritium contains one proton and two neutrons. There is no proton-proton repulsion present in the nucleus. Why, then, is tritium radioactive?

Short answer

Tritium is radioactive because its nucleus, which includes one proton and two neutrons, is unstable. Despite the absence of proton-proton repulsion, the balance between the strong nuclear force and electrostatic force is disrupted due to the additional neutrons, making the atom unstable. To achieve stability, tritium undergoes beta decay, a type of radioactive decay, turning a neutron into a proton while emitting an electron and an electron antineutrino.

Step-by-step solution

Understanding Tritium

Tritium has one proton and two neutrons in its nucleus. This means it is an isotope of Hydrogen, as it has one proton which identifies it as hydrogen. However, the standard hydrogen atom doesn't contain any neutron. Isotopes with extra neutrons are often unstable.

Nuclear Forces and Stability

In a nucleus, there are two types of forces working: the strong nuclear force which keeps the protons and neutrons together and the electrostatic force which creates repulsion between protons. In the case of tritium, there is no proton-proton repulsion, however, the balance between these forces is disturbed because of the extra neutrons.

Cause of Radioactivity

Even though there is no proton-proton repulsion, tritium is still radioactive because its nucleus is unstable. This instability is due to the disturbance in the balance of forces caused by the extra neutrons. To reach stability, tritium emits beta particles from its nucleus. This is a type of radioactive decay.