IYPT 2019 Elements 095: Americium: Smoke detectors and space battery alternative

Element 95 in our International Year of the Periodic Table series is americium. Americium is used in home smoke detectors and could also be used as an alternative to plutonium in space probes in the future.

Americium was discovered in 1944 along with curium – their discovery was linked to the Manhatten project, so their existence remained confidential until the conclusion of World War II. When the time for their official unveiling finally came, one of the scientists involved in the discovery, Glenn Seaborg, pre-empted it. Five days before the announcement, he appeared on a U.S. kids’ radio show. When asked by a caller if any new elements had been discovered, he divulged the synthesis of elements 95 and 96.

Today, microgram amounts of americium are used in home smoke detectors. The alpha radiation emitted by americium ionises air particles and compares the current generated to a sealed reference chamber. If smoke particles enter the ionisation chamber, ionised air particles attach to them and current flow is prevented, triggering the alarm.

In the future, americium may be used as a means of nuclear propulsion for spacecraft. Currently, plutonium is commonly used, but dwindling supplies mean that an alternative may be required in the near future. The European Space Agency has previously considered using americium as an alternative power source.

Remember, you can keep track of all of the previous entries in this series on the site here, or on the Royal Society of Chemistry’s dedicated page.

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