Transcript Chapter 28 Notes, part II Half-life Transmutation Transuranium elements Half-life •Every radioisotope has a specific rate of decay. •It is measured by its half life (t1/2); the.

Chapter 28 Notes, part II
Half-life
Transmutation
Transuranium elements
Half-life
•Every radioisotope has a specific rate
of decay.
•It is measured by its half life (t1/2);
the amount of time it takes for ½ of
a sample to decay into new
elements.
Half-life
•Half-lives of isotopes can range from
billions of years to fractions of a
second.
–Uranium-238 vs. Polonium-214
Half-Life Formula
1 # half lives
(2 )
End amt.=start amt. x
OR
Time elapsed
1 length of h.l.
End amt.=start amt. x ( 2 )
Problem #1
•Nitrogen-15 decays to carbon-13
with a ½ life of 10 minutes. How
long is 3 half lives?
•If there is originally 2.00g of
nitrogen-15, how much remains at
the end of 3 half lives?
Problem #2
•Manganese-56 is a b emitter with a
half life of 2.6 hours. What is the
mass of manganese-56 in an original
1.00mg sample after 10.4 hours?
Problem #3
•A sample of thorium-234 undergoes
decay with a half life of 25 days. If
the original sample is 0.5g how
much is left at the end of 50 days?
Transmutation
•Transmutation is the changing of an
atom of one element into an atom of
another element.
•Radioactive decay (which we have
already seen) is a natural
transmutation. Many times there is
a complex series of reactions that
occur as an unstable isotope
stabilizes, which is called a
reaction series.
Transmutation
•Other transmutations occur in the
laboratory—usually done by
bombarding the nucleus of an
element with high speed particles in
a particle accelerator.
Transuranium Elements
•All elements above the atomic
number 92 are not found in nature;
they are formed in particle
accelerators and nuclear reactors.