We and our surroundings are made of matter, influenced by energy. All matter and all energy comes from stars: we are made of very ancient star stuff.
Chemical groups have set properties, which may be related to their shape, their charge, their preferred charge, their charge distribution, and their size.
We can explain the chemical behaviour of matter in plants, animals, rocks, oceans and the test tube, just by understanding how matter is put together.
All modern chemistry is based on the atomic theory that the behaviour of matter can be explained by assuming it is made of particles, either atoms or molecules.
This file is http://members.ozemail.com.au/~macinnis/scifun/splatschem.htm, first created on February 16, 2008. Last recorded revision (well I get lazy and forget sometimes!) was on February 17, 2009, when it was more-or-less completed. Rome wasn't built in a day, you know!