30-8 Half-Life and Rate of Decay N = -l N D t l Is called the decay constant. Half-life it the time for half of the radio-active nucleus to decay. Radioactive decay law….equation 30-4 DN= No e -lt . DN is number of decays that occur in time t. No is the number of radioactive nuclei present The precise relationship between half-life and decay constant is T1/2 . = .693/ l. 30-6

10-9 continued See Example 30-7 and 30-8

30-10 Decay Series See chart on page 933

30-11 Radioactive dating Using this very accurate ‘clock’ you can determine how much isotope has decayed and determine the age of a radioactive nucleus/element.

30-13 Detection of Radiation Geiger counter Scintillation counter Photo ID

Ch 30 TXTHW 30B P 941 35-40