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Monday, 27 February 2012

Half Life

All the earlier lessons are availble if you search the blog.

Radioactive Half Lives answers.

25s, ~27.5y, ~67d, ~70 min, ~62.5 hrs, ~162 days, ~ 1300y

E25 The Half Life of Radon Gas

a.They decay randomly
b The half life should be measured in variuos places on the graph to establish an accurate value. Approx 55s
c. The long half life of cobalt-60 would mean there was no perceptable change in activity during the short time of a laboratory experiment. 

E26 Ice Age Man 

a. Isotope - different nuclei of the same element, with different numbers of neutrons.
Unstable- incorrect balance of protons and neutrons, leading to emission of particle.
Beta (minus) particle - high energy electron emitted from an unsatble nucleus.
Half life - the time taken for half the nuclei of a given radioactive substance to decay.

b. 6 protons, 8 neutrons

c See main post on Radiocarbon dating

d 11 460 years ago

e it is too old

f The amount of carbon in the atmosphere has risen.