For example, water isn’t on the periodic table because it is a compound, not an element. Water is made from the element hydrogen bonded to the element oxygen. Back to top ...

It is possible under certain conditions, for example in outer space, for helium and other noble gases to become part of compounds.A stable helium compound was created a few years ago, but only ...

Let’s first consider how the periodic table was developed. By the late 18th century, chemists were clear about the difference between an element and a compound: elements were chemically indivisible ...

Elements, compounds and mixtures Separating mixtures - OCR Gateway There are different ways to separate mixtures, for example by filtration, crystallisation, distillation, or chromatography.