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All 118 elements

Element 92 ·actinide

yóu — "uranium"

Uranium

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 由 yóu; watch the shape against 油 yóu 'oil' and 抽 chōu, which share the same right-hand piece.

Where you actually meet it

浓缩铀 (nóngsuō yóu) — enriched uranium

The element itself

The best story in the periodic table is at Oklo in Gabon, where in 1972 French chemists found uranium ore with slightly too little uranium-235 in it. The only explanation that worked was that the deposit had gone critical on its own about 1.7 billion years ago, when U-235 was still abundant enough to sustain a chain reaction, with groundwater acting as the moderator — the reactor switching itself off as the water boiled away and on again as it seeped back, in cycles of a few hours, for a few hundred thousand years. Uranium metal itself is startlingly dense, two thirds again as heavy as lead for the same volume.

Where it sits among the 118

Uranium melts at 1132°C (1405.3 K) — lower than 37 of the 97 elements whose melting point has been measured, and higher than 59. The grey dots are the rest of the table.
In the Earth's crust there is about 2.7 grams in every tonne of rock. That makes it commoner than 44 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 1789.

In Chinese history and language

Uranium in China means one thing above all others: 两弹一星 liǎngdàn yīxīng, "two bombs, one satellite", the compressed shorthand for the crash programme that produced a nuclear device, a missile and an orbiting satellite in barely more than a decade. The first fission test was fired at Lop Nur in the Xinjiang desert in 1964. It is one of the few four-character phrases in modern Chinese that names an entire national project, and it is still used as a byword for doing something difficult under conditions of scarcity.

Where it comes from in China

China's uranium comes in two flavours. Granite-hosted vein deposits sit in the Nanling belt of northern Guangdong and Jiangxi, in the same Mesozoic granite province that gave the region its tungsten, where uranium leached out of the granite was reprecipitated in fractures. The other kind lies in sandstone, in the Ordos basin of Inner Mongolia and the Yili basin of Xinjiang, where oxygen-bearing groundwater carried uranium through porous beds until it met a reducing zone and dropped it; that ore is recovered by pumping solutions down boreholes rather than by digging at all.

Inner Mongolia 内蒙古Xinjiang 新疆Jiangxi 江西Guangdong 广东
Guangdong, Jiangxi, Inner Mongolia and Xinjiang — shaded on a map drawn from Natural Earth's public-domain data.

The full entry

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

Uranium in the dictionary →

Others built the same way

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

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