Elements and compounds

What is an element?

According to modern view, in simpler terms, an element can be defined as a substance made up of atoms of same atomic number.

For example, hydrogen gas, H₂ is an element since the atoms in it have the same atomic number i.e. 1. 

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A chemical compound consists of two are more different types of atoms. For example, water is a compound made up of hydrogen and oxygen. Its formula is H₂O i.e., there are two hydrogen atoms per every oxygen atom.