Warm-Up 10/23/13 Hold Tight! We are changing the seating chart slightly. REMINDER: All warm-ups need to be in your folder by Friday in order to be graded.

Radioisotopes and Radioactivity Wednesday 10/23/13

Radioisotopes Some isotopes are too large, and called radioisotopes. They are described as being “unstable.” Radioisotopes become stable by emitting large amounts of energy (radiation) breaking apart.

Radioactivity A term coined my Marie Curie in 1869 after discovering uranium ore emits rays. It is the process of gaining stability by “radioactive decay”—emitting large amounts of energy to become stable.

Radiation Radiation is the penetrating rays and particles emitted by a radioactive source.

Stability The stability of the nucleus of an atom depends on: Proportion of neutrons to protons in the nucleus The overall size of the nucleus

Types of Radiation There are different methods for becoming a stable nuclei Alpha Beta Gamma Electron Capture Positron Emission

Alpha Decay Helium nuclei (Alpha Particles) emitted to decrease protons and neutrons Large particles, blocked by paper or skin 92 238 𝑈 → 90 234 𝑇ℎ + 2 4 𝐻𝑒

Beta Decay Electrons (beta particles) released in break down of neutrons (n0 to p+ + e-) Smaller particles, blocked by foil or thin wood 6 14 𝐶 → 7 14 𝑇ℎ + −1 0 𝑒

Gamma Decay High energy (not particles) often emitted along with alpha or beta decay. Does not change atomic # or mass. Like x-rays! Dangerous, stopped by meters of concrete or cm’s of lead 94 240 𝑃𝑢∗ → 94 240 𝑃𝑢 + 0 0 𝛾

28 59 𝑁𝑖+ −1 0 𝑒 → 27 59 𝐶𝑜 Electron Capture Electrons captured by the nucleus to convert a proton to a neutron (better n/p ratio). 28 59 𝑁𝑖+ −1 0 𝑒 → 27 59 𝐶𝑜

5 8 𝐵 → 4 8 𝐵𝑒 + +1 0 𝑒 Positron Emission A positron (opposite of an electron) emitted to convert a proton to a neutron (better n/p ratio) 5 8 𝐵 → 4 8 𝐵𝑒 + +1 0 𝑒

Practice From Back Side…

Your Job Finish the problems on the back! We will check them tomorrow. QUIZ Friday on stuff from today!