Re: like BIOchemistry how many chemistry's are there, explain each properly

In no particular order, here are the ones I know about:

Biochemistry: the chemistry of biological (living) systems, like enzyme 
reactions, reactions in the blood, all the DNA and RNA 
reactions,pharmaceutical effects, and so on.  The fact that it is the 
chemistry of living things doesn't mean you do experiments in living 
organisms.  Biochemistry is done in the laboratory.

Organic chemistry: the chemistry of carbon compounds (any compound that 
contains carbon, though carbon dioxide and carbonates are often 
not considered organic.

Inorganic chemistry: the chemistry of compounds that don't contain carbon.

Physical chemistry: the interface between physics and chemistry.  Physical 
chemistry deals with the structure of molecules and the interaction of 
molecules and light, molecules and surfaces (the latter subset is sometimes 
called catalytic chemistry), the details of chemical reactions (how the 
electrons move around), the energy of chemical reactions, thermodynamics, 
spectroscopy, and chemical kinetics (what makes reactions go faster or 
slower.

Theoretical chemistry: mathematical formulations and studies of molecular 
and atomic structure.  Theoretical chemistry is not done in the laboratory.  
The distinction is sometimes made between theoretical and experimental 
chemistry (which is done in the lab).

Environmental chemistry: a new field that deals with chemical reactions in 
the natural environment (e.g., air and water pollution reactions).  
Environmental chemistry includes organic, inorganic, biochemistry, and 
physical chemistry elements.

Radiochemistry: the chemistry of radioactive substances.  Also clearly 
overlaps with all the others.

Solution chemistry deals with solutions.

Gas chemistry deals with reactions in the gas phase.

Then there are some subsets that deal with special section of the periodic 
table: actinide chemistry (chemistry of actinium and the heavier elements - 
uranium, americium, thorium, etc.), transition metal chemistry (iron, 
cobalt, and the other transition elements).


{Editor's note: I'd also include analytical chemistry, the business of learning 
about unknown materials.

Polymer chemistry, which covers the fields of plastics and rubber.

There is absolutely no shortage of chemistries to specialize in!]