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All 118 elements

Element 95 ·actinide

méi — "americium"

Americium

Traditional:

How the character is built

The radical marks this as a metal, and that is not a coincidence of this one character — it holds right across the table. Read the radical first and the element's state at room temperature is already settled. It is (jīn) squeezed into the space beside another component — radicals change shape by position, which is why is hard to spot until you know to look for .

Phonetic 眉 méi 'eyebrow'; Taiwan writes 鋂, also méi.

This character is used for the element and little else — you are unlikely to meet it outside a chemistry classroom.

The element itself

Americium is the only synthetic element most people have owned. A domestic smoke alarm of the older ionisation type contains a speck of americium-241 — well under a milligram — whose alpha particles keep a small current flowing across an air gap until smoke particles interrupt it. It is produced in reactors from the decay of plutonium, and it has a half-life of a few centuries, which is exactly long enough to be useful in a household object and long enough to make disposal a real question.

Where it sits among the 118

Americium melts at 1176°C (1449 K) — lower than 36 of the 97 elements whose melting point has been measured, and higher than 60. The grey dots are the rest of the table.

First isolated in 1944.

The full entry

For stroke order, example sentences, audio and the complete set of meanings, see the dictionary entry.

Americium in the dictionary →

Others built the same way

Every one of these carries , and every one is a metal.

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