21.4+Rates+of+Radioactive+Decay

= = Rates of Radioactive Decay


 * half life - how long it takes for a substance to lose 1/2 of its original nuclei.
 * decay is a first order rxn.
 * decay is unaffected by any sort of effects from the surroundings such as temperature and pressure.

example: half-life chart



Radiometric dating finds the age of an object the becquerel (Bq) is the SI unit, 1 nuclear disintegration per second

Helpful Equations-


 * Rate = kN
 * ln (N_t / N_0) = -kt
 * k = 0.693 / t_1/2
 * above can be switched to find t_1/2 by: t_1/2 = 0.693 / k

N = # radioactive nuclei k = decay constant t = time N_0 = initial # nuclei (at t = 0) N_t = # nuclei remaning after t t_1/2 = half-life

Video showing how to use equation to calculate half-life. The actual camera recording might not be best, randomly goes sideways for a bit, but shows full process and is a word problem, yey!

media type="youtube" key="ovuBao9X56g" height="390" width="480"

Helpful website that goes more into detail about overall section []

Sources:
 * Brown, Theodore L., et al. //Chemistry: the Central Science//. Upper Saddle River, NJ: Pearson Prentice Hall, 2009. Print.
 * "The Rate of Radioactive Decay." __Student Resources for General Chemistry.__ ChemEd DL. 23 March 2011 <[]>.
 * __ Rate of radioactive decay: A worked example to calculate the half life of an isotope __. By ProfEntropy. Youtube. 23 March 2011. <[]>.