RADIOACTIVE ELEMENTS

A Quick Review What makes carbon carbon? What defines an element? The number of protons!!!

How to make carbon not carbon Chemical reaction involve only electrons Nuclear reactions involve the particles in the nucleus (Protons and Neutrons)

Radioactive Radioactive decay: atomic nuclei of unstable isotopes release fast-moving particles and energy

Discovery 1896 French scientist Henri Becquerel Accidently by studying a mineral containing U

Becquerel’s Accident Mineral in sunlight gave off energy Energy could expose film Stored in a dark place and film was still exposed Sunlight was not needed Where did the energy come from?

Radiation U spontaneously gives off energy, we call this radiation, all the time We call this type of radiation radioactivity

Radioactive Elements Polonium Radium Uranium

Types of Radioactive Decay Alpha Decay Beta Decay Gamma Decay (Radiation)

Alpha Decay Isotope gives off an Alpha Particle Alpha Particle: 2 Neutrons and 2 Protons Losses 4 mass Losses 2 atomic number Thorium – 232 gives off an Alpha Particle and becomes radium - 228

Beta Decay Isotope gives off a Beta Particle Beta Particle: Neutron turns into a proton, this shoots out an electron Mass does not change Atomic number goes up 1 Carbon – 14 becomes nitrogen - 14

Gamma Decay Happens with Alpha and Beta Decay Element gives off high energy ways called gamma rays No charge Does not change the mass Does not change the atomic number

Effects of Radiation Alpha particles move fast and stopped by colliding with other atoms Causes a bad burns

Effects of Radiation Beta particles move faster and more penetrating (can not pass through 5mm sheet of Al) Travels into the body and damages cells

Effects of Radiation Gamma rays travel faster yet and penetrate even more Goes through the human body delivering intense energy and damage to cells

Using Radioactive Isotopes Determining age of natural things Tracing chemical reactions and industrial possesses Diagnosing and treating disease Providing sources of energy

Dating Not all atoms decay at once Happens randomly (can not predict) Can measure when half the elements will decay by This measure is called half-life

Half-Life Length of time needed for half of the items in a sample to decay Different for each isotope Range from less then a second to billions of years Pg 143

Radioactive Dating Measure carbon – 14 in organic material After it dies it stops taking in carbon Count half-lives Gives an estimate of how old fossils and rock are.

Older dating Carbon – 14 is only useful up to 60,000 yrs Use other elements for earlier materials Potassium – 40 Uranium - 238

Science and Industry Tracers: chemicals that can be followed through the steps of a chemical reaction Phosphorus - 32 in plants Gamma rays detect weakness in metals Shows on photo film

Medicine Tracers of technetium – 99 Diagnose problems in bones, kidneys, digestive system Radiation therapy Iodine Cancer cells Cobalt - 60

Power Nuclear Power Plants Nuclear Submarines Uranium - 235

Chernobyl

Safe Use Radiation is harmful! Isolated clothing Bury in the ground Will decay according to half- life