20-4 Radioactive Elements

Nuclear Reaction  Involve the particles in the nucleus of atoms  Can change one element into a new element if the number of protons are changed

Isotopes  Atoms with the same number of protons, but different number of neutrons  12 C has 6 protons and 6 neutrons  14 C has 6 protons and 8 neutrons

Radioactive Decay  Nuclei of unstable isotopes release fast- moving particles and energy. 3 types: 1. Alpha Decay – 2 protons & 2 neutrons are released 2. Beta Decay – 1 proton is added & 1 neutron is subtracted 3. Gamma Decay – doesn’t change number of protons or neutrons, but gives off gamma rays

Alpha Decay Beta Decay ***

Half-Life  Length of time needed for ½ of the atoms of a sample to decay  ½ life is different for each isotope  ½ life is useful in determining the ages of rocks and fossils = radioactive dating

Problems & Uses  Radioactivity, especially gamma radiation, can damage the cells of living organisms  Nuclear reactions release enormous amounts of energy, & are used in nuclear power plants  Radiation therapy uses radioactive elements to destroy cancer cells  Radioactive isotopes are used as tracers and to diagnose disease  Problem of disposing radioactive waste

In a nuclear reaction what can change? 1. Number of protons 2. Number of electrons 3. Number of neutrons 4. Both #1 &

What is an isotope? 1. An atom with a different # of protons 2. An atom with a different # of electrons 3. An atom with a different # of neutrons 4. None of the above of 40

Alpha, beta, & gamma decay all produce a new element. 1. True 2. False of 40

½ life of a radioactive element can vary with the conditions under which it occurs. 1. True 2. False of 40

Which of the following is not a use of radioactive isotopes? 1. Radiation therapy 2. To produce electricity 3. To make salt 4. As tracers of 40

Which type of radiation is most harmful to living things? 1. Alpha decay 2. Beta decay 3. Gamma decay of 40