Hi Mara :) <3
chemicals
Lots of people. Hundreds of thousands, in fact. If you expected us to list them all for you, guess you're going to be disappointed.
That depends on exactly what you mean by "components". You might want to try asking your question again in a less ambiguous way.
space is studied in chemistry.
chemical compound (a substance consisting of two or more different elements chemically bonded together in a fixed proportion by mass)