Coronium

Coronium (コロニウム Koroniumu), abbreviated as Cw, is a metallic element. It is a synthetic element that exists as a gas at room temperature.

Properties
As a gas, coronium is highly reactive and pyrophoric, meaning it will spontaneously ignite when exposed to oxygen. It is also capable of ripping oxygen from oxides, such as water and organic matter, leaving only the constituent elements such as hydrogen and carbon.

As a liquid, coronium is significantly less reactive, though it will still quickly oxidize in the presence of oxygen.

Coronium poisoning (コロニウム中毒 Koroniumu Chūdoku) is caused by inhaling coronium gas, which is rare because of its pyrophoricity. In small doses, it can cause asphyxiation, but larger doses can cause severe internal damage as it will literally burn organic matter.

Trivia

 * It is named after Aegis D. Crown, who synthesized it.

Etymology
Coronium comes from Latin corona, "crown," which in turn comes from Ancient Greek κορώνη korōnè, "garland, wreath," and the suffix -ium, which is used to denote elements. Cw comes from crown because C, Cr, and Co are already being used.