Shine On You Crazy Radioisotope: Nuclear Chemistry, Use or Abuse
Have you heard of radioactive dating? No, it’s not a romantic interlude, but another
powerful aspect of Nature that humans can use or abuse. Scientists use radioactive
isotopes of particular elements to determine the absolute age of human artifacts as well as
the age of the Earth. They use certain radioisotopes in medicine and science experiments
to track the pathways of particular molecules or drugs. And radioactive isotopes can
provide carbon free electricity or be used to unleash the most destructive weapons ever
seen. At the turn of the last century, scientists discovered something very curious about
certain isotopes of heavy atoms; they can emit three types of radiation: alpha, beta and
gamma. It turns out that as the number of protons increase as we advance across and
down the periodic table, the number of neutrons grows even larger. When a particular
ratio of neutrons to protons is particularly high, the isotope is unstable and begins to
decay into another element and emit radiation. Alpha particles are 2 protons and 2
neutrons, beta particles are electrons and gamma rays are high energy waves (not
particles). All radioisotopes decay at a rate that can be used as a clock and have a half
life that can be measured in sample of radioisotopes. A half life is the time it takes for
half the radioisotope to turn into another element. Since some radioisotopes have half
lives in billions of years they can be used to date rocks as old as the Universe itself! But
many radioisotopes decay quickly leaving only high energy light in their dying wake.
How much energy is released? The energy released comes from matter than is turned
into energy and follows Einstein’s famous equation E=mc2. Einstein’s equation tells
us that a tiny amount of mass can be converted into a huge amount of energy. Since
radioisotopes release energy we can use them to provide electricity for our homes and
industry as well as power the batteries aboard remote spacecraft. Nuclear power plants
big and small rely on releasing gamma rays slowly in a controlled fashion to create
thermal energy to boil water and run turbines. By releasing this energy quickly we can
unleash an awful amount of destructive power in a nuclear bomb. The first nuclear
bombs were dropped during World War II to end the war with Japan. Some important
radioisotopes include isotopes of uranium and plutonium used in nuclear power plants
and nuclear bombs and carbon, potassium, cesium and rubidium used in dating
artifacts and earth materials. Radioisotopes of Iodine, Phosphorous and Technetium
are used in medial applications to target cells and trace the pathways of drugs.
Answer the questions below.
1. What can radioisotopes be used for?
2. What are the three types of radiation? Describe each one.
3. What is a half life? Can radioisotopes be used to find the absolute age of things?
4. What famous equation describes the release of energy in radioisotopes? When and
where were nuclear bombs first used? What are some important radioisotopes and how
are they used?