How the character is built
The 钅 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 金 (jīn) squeezed into the space beside another component — radicals change shape by position, which is why 金 is hard to spot until you know to look for 钅.
Phonetic 拿 ná 'to take'; Taiwan writes 錼 nài instead.
This character is used for the element and little else — you are unlikely to meet it outside a chemistry classroom.
The element itself
Neptunium was the first element made beyond uranium, and it was named on the same logic that had named uranium after a planet — the next one out. It does occur in nature, but only just: uranium ore contains fantastically small amounts, formed when a uranium nucleus happens to catch a stray neutron rather than being left over from the planet's formation. Everything anyone has ever worked with came out of a reactor, where it builds up as a by-product with a half-life of two million years — long enough that it is still there to be reckoned with after the fission products have burned themselves out.
Where it sits among the 118
First isolated in 1940.
The full entry
For stroke order, example sentences, audio and the complete set of meanings, see the dictionary entry.
镎Neptunium in the dictionary →Others built the same way
Every one of these carries 钅, and every one is a metal.