Hydrogen:
We all know by now that hydrogen is the first element of the periodic table. It is the simplest of all atoms. It just has one proton. It is the only atom that has no neutron.
The hydrogen atom has only one electron. It combines with another hydrogen atom to form a complete duplet, and thus makes a molecule of hydrogen H2. Hydrogen in its original state exists always as a diatomic molecule, i.e. it is always in the form of H2.
If we need to test for hydrogen, we take a lighted splint near the mouth of the suspected hydrogen. If there is a loud ‘pop’ sound, it means that the gas is hydrogen.