AST101H5 Lecture : AST101-Chapter 6&7.txt
Document Summary
1. to determine earth"s general planetary properties (some of this is from cha pter 6) 2. to use earth"s general properties to guide our investigation of other plane ts - particularly the other terrestrial planets. Earth"s age is measured using methods from chapters 5 and 6. Recall chemical elements occur as different isotopes (chapter 5). 1. examples: carbon - 12 = 12c (6 protons and 6 neutrons), 13c = (6 protons and 7 neutrons) and 14c = (6 protons and 8 neutrons). Radioactive isotopes are unstable, they change (or decay) spontaneously int: isotopes of other elements, emitting particles. The rate of decay does not depend on the environment (temp, pressure, ) The rate of decay depends only on the properties of the atomic nucleus. The decay rate is expressed as the half-life = time for the isotopes present to convert. Radioactive carbon-14 -> nitrogen-14 with a half-life of 5730 years.
