Radioactivity and Radiation
Forms of Energy • The five main forms of energy are: – Heat – Chemical – Electromagnetic – Nuclear – Mechanical
Nuclear Radiation Many elements can change through radioactivity. -Radioactive elements have unstable nuclei. -Radioactive elements can decay. – Emit radiation – Can become a different isotope of the same element – Can become a different element!
Types of Radiation • Alpha Particle – Helium nucleus with a + 2 charge – The largest radioactive particle – Don’t penetrate very deep
• Beta Particle – A fast moving electron -1 charge – Can travel through paper, but wood or aluminum will stop it.
• Gamma Particle – Tiny and too small to measure (like photons) – No charge – Travel through clothes and even walls
www.geology.fau.edu/course_info/fall02/ EVR3019/Nuclear_Waste.ppt
Alpha decay Alpha particle has a mass of 4. -- 2 protons and 2 neutrons --Mass goes down by 4 --Atomic # goes down by 2
6
Beta decay Beta particle has an tiny mass. -- A neutron is converted to a proton --Mass stays the same --Atomic # goes up by 1 234Th 90
→
234Pa 91
+ 0e −1
beta particle 7
Gamma radiation No change in atomic or mass number 11B 5
11B 5
+
0
γ
0
8
Comparison of Chemical and Nuclear Reactions Chemical Reactions Occur when bonds are broken or formed Involve only valence electrons Associated with small energy changes
Nuclear Reactions Occur when nuclei combine, split, & emit radiation Can involve protons, neutrons, & electrons Associated with large energy changes
Atoms keeps same identity Atoms of one element are although they may gain, often converted into atoms lose, or share electrons, of another element and form new substances Temperature, pressure, concentration, and catalysts affect reaction rates
Temperature, pressure, and catalysts do not normally affect reaction rates