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All 118 elements

Element 94 ·actinide

bù — "plutonium"

Plutonium

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 不 bù; Taiwan uses a different character, 鈽, with exactly the same reading bù.

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

The element itself

Plutonium is a metallurgical nightmare in a way few people expect: it exists in six different crystal forms between room temperature and melting, some of which are markedly less dense than others, so a piece of it can change volume by several percent simply on warming. It is a poor conductor for a metal, warm to the touch from its own decay, and alloying is used to hold it in a single stable phase. Trace amounts occur naturally in very rich uranium ore through neutron capture, but for practical purposes it is a reactor product.

Where it sits among the 118

Plutonium melts at 639°C (912.5 K) — lower than 62 of the 97 elements whose melting point has been measured, and higher than 34. The grey dots are the rest of the table.
In the Earth's crust there is present only in traces, far below a milligram per tonne. That makes it commoner than 5 of the 93 elements that occur naturally at all. The scale is logarithmic: each gridline is ten times the one below it.

First isolated in 1941.

The full entry

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

Plutonium in the dictionary →

Others built the same way

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

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