02 Isotopes.notebook
February 22, 2017
Isotopes of Atoms
Isotopes are atoms that have the same number of
protons, but different numbers of neutrons.
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02 Isotopes.notebook
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Isotopes
number of neutrons in an atom can vary
same chemical proper es
different physical proper es
some isotopes are stable, while others decay over me
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02 Isotopes.notebook
February 22, 2017
Radioisotopes
unstable isotopes
release radia on and become other atoms (e.g carbon 14
--> nitrogen -14 + beta par cle)
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02 Isotopes.notebook
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Radioisotopes are useful for many prac cal uses:
radioac ve decay can be detected and used to
trace the movement of atoms in a living organism
the amount of an isotope present in a material can
be used to determine a date when it died (e.g. logs
cut down for a boat)
beta par cles can be used for radiotherapy
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02 Isotopes.notebook
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Radioisotope Tracers
Iodine has two common isotopes I-127 and I-129
A pa ent can ingest a pill containing I-129 and then a
using an image of the radia on can be produced and
mapped onto the ssues of the pa ent (e.g. distribu on
of iodine in the thyroid gland)
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Carbon Da ng
the atmosphere has a constant amount of C-14
living plants add these atoms to their structure as they grow
once dead, the C-14 decays at a regular rate allowing a date
to be determined
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Rela ve Atomic Mass
75.77% of chlorine atoms consist of the Cl-35 isotope, while
24.23% of chlorine isotopes are Cl-37. What is the average
atomic mass of chlorine?
A pure sample of an element contains all the possible isotopes
for that element.
The mass of a pure isotope would always be a whole number
(mass number), whereas the mass of a pure element is a
weighted average.
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