Chapter 4: Atomic Energy

The French scientist Henri Becquerel is credited with the discovery of radioactivity. While studying a uranium compound in 1896, he noticed that the uranium gave off an invisible form of energy.

Radioactivity is the process by which an unstable nucleus gives off nuclear radiation. Plutonium Uranium

One of Becquerel’s students, Marie Curie, discovered 2 new radioactive elements, radium and polonium.

The radiation given off by radioactive elements consists of three types of particles or rays: alpha beta gamma

Alpha Particles: consists of 2 protons and 2 neutrons and has a positive charge. Alpha particles are the weakest type of nuclear radiation! Symbol: 

Beta Particles: consist of a single electron, contains no protons or neutrons, 10 times stronger than alpha particles. Symbol: 

It was Gamma radiation that produced: Gamma Rays: these are electromagnetic waves, these are the strongest form of radiation. Symbol:  It was Gamma radiation that produced:

Many stable elements have other forms that are radioactive Isotopes: atoms of the same element that have different numbers of neutrons.

Effects of Radiation on the Human Body Exposure to radiation can cause radiation sickness. Because radiation damages the body’s tissues, it can also lead to cancer and death.

Atoms that are unstable can become stable by radioactive decay Atoms that are unstable can become stable by radioactive decay. This is the spontaneous breakdown of an unstable atomic nucleus.

The fixed rate of decay of a radioactive element is called half-life The fixed rate of decay of a radioactive element is called half-life. This is the amount of time that it takes ½ of the atoms in a sample to decay to a stable state. The most important use of radioactive half-life is to determine the age of a fossil or rock.

Example: C-14 has a half-life of 5730 years Example: C-14 has a half-life of 5730 years. This means that if you are given a 100g sample of C-14, after 5730 years you would have 50g of C-14 and 50g of stable Carbon. 100g  50g  25g 12.5g

Nuclear Fission: the splitting of an atomic nucleus into 2 smaller nuclei that are the same size. These by themselves do not create much energy, but they start a nuclear chain reaction, which causes other nuclei to split. The end result is a large amount of energy! Examples: the atomic bomb, nuclear power

How a Nuclear Power Plant Works Uranium undergoes fission and releases heat This heat is used to boil water Steam turns a turbine attached to a generator Magnets inside the generator create electricity

Nuclear Fusion: the joining of 2 atomic nuclei to form a single nucleus. In order to occur, these reactions require a temperature over 1 million degrees Celsius! Examples: Hydrogen bomb, sun