Hi,
Hydrogen is the simplest known atom on the planet and is the lightest element. The number of proton and electron is one. It is the first element in the periodic table. It is also one of the first ever element to be formed on earth millions of years ago.
Halogens are non metal elements. They are fluorine, chlorine, bromine, iodine and astatine.
The common salt we use every day is NaCl (Sodium Chloride). These elements when combine with metals usually give salts, like NaBr(Sodium Bromide), CaCl2 (Calcium Chloride).