Question

Why hydrogen and oxygen are considered elements whereas water is a compound?

Answer 1

Reason

1. Elements – Elements constitute the simplest chemical substances in which all the atoms are exactly the same.
2. Compounds – Compounds are chemical substances made up of two or more different types of elements that are chemically bound together in a fixed ratio.
3. Hydrogen$\left({\mathrm{H}}_2\right)$ and Oxygen$\left({\mathrm{O}}_2\right)$ are considered elements because they contain just one type of atom.
4. Whereas water$\left({\mathrm{H}}_2\mathrm{O}\right)$ is a compound since it has two types of atoms (Hydrogen & Oxygen).