Compound

A compound is a group of atoms. A chemical formula specifies the number of atoms of each element in a compound, using the standard abbreviations for the chemical elements and subscripts. For example, a water molecule has formula H2O indicating two hydrogen atoms plus one oxygen atom. Globally, more than 350,000 chemical compounds have been registered for production and use in our local planet.

Reactions
A compound when mixed with a different compound usually results in another compound and a chemical reaction. Using the chemical formula from earlier, if A is the first compound, B is the second compound, and C is the third compound, this is denoted as A+B => C.