Radiation Chp 24

25,000 mrem 500,000 mrem

Radiation is discovered coming from matter In late 1890's, scientists noticed some substances decayed or spontaneously emitted rays and particles called radiation.

Why is radiation emitted from atomic nuclei? 1:1 to 1.5 : 1 is the stable neutron:proton ratio in the nucleus. Any nuclei outside this ratio is unstable and will undergo decay to gain stability.

Band of Stability These unstable (radioactive) nuclei lose energy by emitting radiation until they form into stable atoms, often a different element. For nuclei with atomic #'s 83 and greater, these are all unstable and will decay and emit radiation.

Nuclear equations show atomic # and mass # involved, both sides will have same sum

Nuclear equations show atomic # and mass # involved, both sides will have same sum 234 92

Alpha decay will decrease both the number of protons and neutrons

Alpha decay will decrease both the number of protons and neutrons 216 84 4 2 230 89 He + Ac Po 212 82 Pb

Beta decay will increase the number of protons in the nucleus.

Beta decay will increase the number of protons in the nucleus. Pa 216 85 -1 e + 210 84 Po 239 93 Np

gamma emission has no effect on the number protons and neutrons in the nucleus

Positron emission will decrease the number of protons

Positron emission will decrease the number of protons

Electron capture will decrease the number of protons

Electron capture will decrease the number of protons

Practice Problems 6-8 pg 869 6. Write a balanced nuclear equation for the reaction in which oxygen-15 undergoes a positron emission. 7. Thorium-229 is used to increase the lifetime of fluorescent bulbs. What type of decay occurs when thorium-229 decays to radium-225?

Practice Problems 6-8 pg 869 O e N Th Ra α 6. Write a balanced nuclear equation for the reaction in which oxygen-15 undergoes a positron emission. 7. Thorium-229 is used to increase the lifetime of fluorescent bulbs. What type of decay occurs when thorium-229 decays to radium-225? 15 8 O +1 e 15 7 N + 229 90 Th 225 88 Ra 4 2 α +

8. Bismuth-212 decays producing isotopes A which then undergoes a second decay producing isotope B. Write a balanced nuclear equation for both decays.

8. Bismuth-212 decays producing isotopes A which then undergoes a second decay producing isotope B. Write a balanced nuclear equation for both decays. 212 83 Bi -1 e 212 84 Po + 212 84 Po 4 2 α 208 82 Pb

Americium-242 is a radioisotope in smoke alarms. It emits Americium-242 is a radioisotope in smoke alarms. It emits ?alpha particles that ionize to produce a current in the air. When smoke interfers with this, a microchip triggers the alarm. Write a balanced nuclear reaction for the decay of americium-242 Should you be concerned about this radioisotope being in your home?

Americium-242 is a radioisotope in smoke alarms. It emits Americium-242 is a radioisotope in smoke alarms. It emits ?alpha particles that ionize to produce a current in the air. When smoke interfers with this, a microchip triggers the alarm. Write a balanced nuclear reaction for the decay of americium-242 Should you be concerned about this radioisotope being in your home? 242 95 Am 4 2 He 238 93 Np + No, alpha decay is easily blocked.

Classify Each Nuclear Equation

Classify Each Nuclear Equation Alpha Beta Positron Emission Electron Capture