1. DE Chemistry – King William High School

2.  Radiation – small particles of energy that are spontaneously emitted from unstable nuclei that is radioactive  Radioisotope – an isotope of an element that emits radiation  Atomic number 93 and higher are man made and only have radioactive isotopes  Radioactive isotopes are named by writing the mass number after the name (iodine-131)

3.  An unstable nucleus becomes more stable by emitting radiation and forming a lower energy nucleus  Alpha particle (  ) – helium nucleus  4 2   Beta particle (  ) – a high energy electron  0 -1 e or 0 -1   Positron – an unstable nucleus transforms a proton into a neutron and a positron ( 0 +1  )

4.  A positron is an example antimatter  Antimatter – a particle that is the opposite of another particle  When a positron and electron collide their masses are converted to energy in the form of gamma (  ) rays  Gamma rays – high energy radiation ( 0 0  )

5.  Proton – hydrogen ( 1 1 H)  Neutron ( 1 0 n)

6.  Rapidly dividing cells are most susceptible to radiation (bone marrow, skin, reproductive organs and intestinal lining…and ALL cells in growing children)  Cancer cells rapidly divide. That’s why we treat with radiation…radiation kills carcinoma at a faster rate than normal, healthy cells

7.  Read radiation protection on page 137-8!  Notes gamma rays are the most dangerous because they penetrate deeply

8.  Radioactive decay – nucleus spontaneously breaks down by emitting radiation  Alpha decay – unstable nucleus emits an alpha particle 238 92 U  234 90 Th + 4 2 He  EX: 241 95 Am  + 4 2 He

9.  Beta decay – breakdown of a neutron into a proton and electron 14 6 C  14 7 N + 0 -1 e  EX: 90 39 Y  + 0 -1 e

10.  Gamma decay is rare  Example – technetium (Tc)…the unstable isotope if given the symbol m (metastable) 99m 43 Tc  99 43 Tc + 0 0 

11.  Usually produced in small amounts by converting stable (nonradioactive) nuclei into radioactive ones  Transmutation – a stable nucleus is bombarded by high speed particles 4 2 He + 10 5 B  13 7 N + 1 0 n bombarding particle + stable nucleus  radioactive isotope + neutron

12.  Geiger counter – used to detect beta and gamma radiation  Curie (Ci) – number of disintegrations of a substance per second  SI unit is the becquerel (Bq)  RAD (radiation absorbed dose) – the amount of radiation absorbed by a gram of material (i.e. body tissue)  Read pages 145-147

13.  Is the amount of time it takes for ½ of a sample to decay  EX: a 20 mg sample of iodine-131 has a half- life of 8.0 days…how much is left after 32 days?

14.  Read pages 152-155

15.  Fission – energy created by splitting the atom (atomic energy) 235 92 U + 1 0 n  236 92 U  91 36 Kr + 142 56 Ba + 3 0 n The mass of the products is less than the starting materials…the missing mass has been converted into BIG amounts of energy. Remember Einstein (E = mc 2 ) NOTE: 1 g U = 3 tons of coal

16.  Look at visual on page 156

17.  Two small nuclei combine to form a larger nucleus 3 1 H + 2 1 H  4 2 He + 1 0 n + energy EX: sun/stars constantly have fusion reactions occurring (producing heat and light)