How did earlier chemist know they had discovered a new chemical element?


I’m sure there’s a highly technical way of doing this today, but how did chemists in the 18th century know that what they had produced was a pure and uknown chemical element, and not just another chemical compound?

In: 4

Water was thought to be an element till late 18th century (1783), when they combined hydrogen and oxygen and got water, proving it as a compound.

So, they didn’t, till they could prove otherwise.

They made the best educated guess they could based on the available evidence they had at the time. This is true of anything in science, even today. Sometimes we’re wrong, but when we’re wrong, that’s good because it means we get to add to our body of knowledge.

If you can’t split it into components with any known method and if you can reproduce its properties with different samples there is a decent chance it’s an element. That process is not without issues and has produced some “elements” that were later shown to be a mixture of more than one element (e.g. “columbium”, later split into niobium and tantalum).

Many elements also follow predictable patterns, so if you have something that fits in a gap it’s more likely to be an element instead of a compound.