Periodic Table of WIS

Americium Am

 

Where is americium used--or where does it impact your everyday life?

 

Americium is a synthetic element--made in very small quantities

 

 

Some smoke detectors contain a small sample of americium-241.  As they sit on your wall, the americium-241 is producing very small amounts of alpha particles (helium nuclei) from radiactive decay:   24195Am --> 23793Np + 42He        The half life of americium-241 is 458 years.  If smoke particles enter the smoke detector, they restrict the detection of the alpha particles from the radioactive decay of americium-241.  This reduction triggers the alarm.

 

{Reminder: alpha particles are the least penetrating radioactive emission.  They are helium nuclei--so VERY small but are blocked by an index card, clothing and even skin and a few centimetres of air.

Beta particles [NOT present in a smoke detector] are more penetrating and are high energy electrons--even smaller than alpha particles--but they can be blocked by a few millimetres of aluminum.

Gamma radiation os the most penetrating of all radioactive emissions--and is short wavelength ray that will pass through meters of concrete and quite a few centimetres of lead--also NOT in a smoke detector}