Question

Which isotope of hydrogen is radioactive? Write the nuclear equation for the radioactive decay of this isotope.

Short answer

The radioactive isotope of hydrogen is tritium (${}_1^3$H). Its radioactive decay occurs through beta decay, and the nuclear equation for this process is $${}_1^{3}H{\to }_2^{3}He{+}_{-1}^{0}e$$. In this equation, tritium decays into a helium-3 nucleus (${}_2^3$He) and a beta particle (an electron: ${}_{-1}^{0}e$).

Step-by-step solution

Identifying Hydrogen Isotopes

Hydrogen has three known isotopes: protium (${}_1^1$H), deuterium (${}_1^2$H), and tritium (${}_1^3$H). Protium is the most common isotope and has one proton and no neutrons. Deuterium has one proton and one neutron. Tritium has one proton and two neutrons.

Determining the Radioactive Hydrogen Isotope

Among the three hydrogen isotopes, tritium (${}_1^3$H) is radioactive. Tritium undergoes radioactive decay by emitting a beta particle.

Writing the Nuclear Equation for Radioactive Decay of Tritium

Now, we need to write the nuclear equation for the radioactive decay of tritium. A beta decay occurs when a neutron in an unstable nucleus turns into a proton and emits an electron, called a beta particle. The atomic number (Z) of the resulting element increases by 1, while the mass number (A) remains the same. The nuclear equation for the beta decay of tritium can be represented as: $${}_1^{3}H{\to }_2^{3}He{+}_{-1}^{0}e$$ Here, tritium decays into a helium-3 nucleus (${}_2^3$He) and a beta particle (an electron: ${}_{-1}^{0}e$).