Explain the type of decay, the half-life, and the chemical properties of iodine 131, and why it is used for monitoring of thyroid gland.

Iodine 131 is a radioisotope of the element
iodine. It is a radioactive material and undergoes decay. This means that its concentration
decreases over time. The half-life (the time taken by a substance to decay to 50% of its
original value) of iodine 131 is 8.02 days, which is very short. This means that if we start
with a 100 gm of iodine 131, after 8.02 days, we will be left with only 50% or 50 gm of it.

Iodine 131 undergoes first-order decay. This means that the rate of decay is
directly proportional to its concentration and the decay is exponential. It decays into xenon
131.

As already mentioned, it is a radioactive material and has an atomic
mass of 131 gm. It is a non-metal and emits beta and gamma particles.

It is
used in medicinal sciences, in small doses, for thyroid cancer therapy. It accumulates
selectively in the thyroid gland and kills the thyroid cells through its radioactivity. It also
decreases thyroid hormone production in our bodies. It can also be used for the treatment of
hyperthyroidism and for the study of the proper functioning of our thyroid gland.

It is an ideal tracer for studying the functioning of our thyroid gland because the
iodine atoms attach exclusively to the thyroid gland, once these atoms are injected into our
bloodstream. We can then use the Gamma-ray scintigraphy to study any anomalies that may appear.

Hope this helps.

href="http://www.radioactivity.eu.com/site/pages/Iodine_131.htm">http://www.radioactivity.eu.com/site/pages/Iodine_131.htm
href="https://pubchem.ncbi.nlm.nih.gov/compound/Iodine-131">https://pubchem.ncbi.nlm.nih.gov/compound/Iodine-131