Nuclear Fission and Fusion

What is an isotope?

All of the chemical reactions that we have discussed have involved only the exchange of electrons on the outside of the nucleus. Elements with the same number of protons but different number of neutrons (such as tritium, deuterium, and protium — are all forms of hydrogen having one proton and three, two, and one neutron respectively) and are called isotopes. Sometimes elements with unstable nuclei (due to larger numbers of protons and neutrons) can lose nuclear particles that change the number of either protons or neutrons in the nucleus. These are called radioactive elements because a large amount of energy is usually released as the nucleus loses mass. As the nucleus decays, the atoms of one element are transformed into the atoms of another element. This is called natural transmutation. For elements greater than number 83, this produces isotopes that are radioactive, also known as radioisotopes.

Radioactive decay

Radioactive elements follow a predictable rate of decay based on their known half-life. These reactions are similar mathematically to the rate of reaction discussed earlier. As the parent atoms decrease, the daughter atoms increase proportionally.

• Fission: the energy contained in the heavy nucleus of the atom overcomes the forces that bind the nucleus together. Uranium and Plutonium are common elements used in nuclear reactors that make use of this process.
• Fusion: the energy released when two light nuclei fuse to form a heavier nucleus. The sun’s energy is a result of these type reactions where hydrogen atoms combine to form helium.