What is one practical use of the element americium?

1 Answer
Jan 8, 2017

The most important use of americium is in home smoke detectors.


How does a smoke detector work?


Americium-241 decays mainly by α-decay with a half-life of 242 years:

#""_95^241"Am" → ""_93^237"Np" + ""_2^4"He"#

Smoke alarm
(From BC Open Textbooks)

About 200 µg of #"AmO"_2# is sealed inside an ionization chamber in the smoke detector.

The α-particles strike the nitrogen and oxygen molecules in the air, causing them to form ionized molecules and free electrons.

The electrically charged particles help carry a current from between two charged metal plates.

The current flows if there is only air in the detector.

If smoke enters the detector, the ions attach to the smoke particles and neutralize them.

This decreases the current and triggers an alarm.