1. Nuclear Chemistry Ch. 21

2. Radioactive Emissions

3. Alpha decay – He nucleus What product is formed when radium-226 undergoes alpha decay? What element undergoes alpha decay to form lead-208?

4. Beta particles – created by the conversion of a neutron in the nucleus to a proton and an electron (beta particle); the proton remains in the nucleus while the beta particle is ejected Iodine-131 undergoes decay by beta emission Lead-209 undergoes decay by beta emission

5. Electron Capture An inner shell electron is pulled into the nucleus where it combines with a proton to form a neutron; so atomic number decreases by 1, but atomic mass stays the same Mercury-201 undergoes electron capture

6. Gamma Rays – does not result in a change in the property of the atom

7. X A Z Mass Number Atomic Number Element Symbol Atomic number (Z) = number of protons in nucleus Mass number (A) = number of protons + number of neutrons = atomic number (Z) + number of neutrons A Z 1p1p 1 1H1H 1 or proton 1n1n 0 neutron 0e0e 00 or electron 0e0e +1 00 or positron 4 He 2 44 2 or  particle 1 1 1 0 0 0 +1 4 2 23.1

8. Learning Check What radioactive isotope is produced in the following bombardment of boron? 10 B + 4 He ? + 1 n 5 2 0

9. Learning Check What radioactive isotope is produced in the following bombardment of boron? 10 B + 4 He 13 N + 1 n 5 2 7 0

10. Half-Life Time required for half of any given quantity of a substance to react