2.  The spontaneous emission of radiation › Created by unstable nuclei of very heavy elements › Radioactive elements can give off 3 types of radiation:  Alpha:  helium nuclei  can usually be stopped by a piece of paper  Beta:  e- which are much smaller and lighter than alpha particles  More penetrating power than alpha particles  Can be stopped by a thick wooden board  Gamma  Extremem energetic form of light  VERY powerful  Several inches of lead of several feet of concrete necessary to stop them

3.  Atomic Number: › is the number of protons in the nucleus › The Lithium atom has three electrons occupying 2 energy levels and three protons giving it an atomic number Z = 3.  Atomic Mass: › is the number of particles in the nucleus. › The Lithium nucleus includes four neutrons and 3 protons making up its seven particles and thus a mass number A = 7  Atomic Structure: › Lithium-7 or 7 Li › The mass number is placed after the name of the element or is indicated as a superscript preceding the chemical symbol. › 7 Li 3 › The symbol may also indicate the full atomic structure by adding a subscript representing the atomic number.

4.  Write the nuclear notation for the following:  Li  U  Pb

5.  Uranium-238 decays to form Thorium-234, a radioactive silvery metal, with the emission of one Helium atom. Thus 238 U 92 ⇒ 234 Th 90 + 4 He 2  The daughter nuclide (thorium-234) has 2 fewer protons and neutrons than the parent nuclide (uranium-238)

6.  A radioactive elements distinctive rate of decay  The amount of time it takes ½ of radioactive material to decompose

7.  A radioactive isotope has a half-life of 12.4 hours. If a lab starts with a 13.2 mg sample how much will remain after 37.2 hours?  13.2/2 /2 /2 = 1.65 mg  A radioactive substance has a half-life of 10 years. How much is left after 30 years?  ½ of ½ of ½ or 1/8

8. Procedure and Questions 1&2 Monday April 18

9. Wednesday April 20

10.  The fission process take place when the nucleus of a heavy atom, like uranium or plutonium, is split in two when struck by a neutron.  The "fissioning" of the nucleus releases two or three new neutrons.

11. 1 0 n + 23 592 U  132 50 Sn + 101 42 Mo + 3 1 0n 1 neutron bombards 1 heavy element and it disintegrates into 2 smaller nuclei and 2-3 neutrons

13. 4 1 1 H + 2 0 -1 e  4 2 He

14. All Group Analysis Questions Wednesday April 20