CHAPTER 1. ORGANICMOLECULES 1.
1.2 Sources of carbon
ESCB
The main source of thecarbon in organic compounds is carbon dioxide in the air.
Plants use sunlight to convert carbon dioxide into organic compounds through the pro-
cess of photosynthesis. Plants are therefore able to make their own organic compounds
through photosynthesis,while animals feed on plants or plant products sothat they gain
the organic compoundsthat they need to survive.Another important source of carbon is fossil fuels such as coal, petroleumand natural
gas. This is because fossil fuels are themselvesformed from the decaying remains of
dead organisms (refer toGrade 11 for more information on fossil fuels).1.3 Unique propertiesof carbon
ESCC
Carbon has a number of unique properties which influence how it behaves and how it
bonds with other atoms:- Carbon has four valence electrons which means that eachcarbon atom can form
four bonds with other atoms. Because of this,long chain structures can form.
These chains can eitherbe unbranched (figure 1.1) or branched (figure 1.2). Be-
cause of the number ofbonds that carbon canform with other atoms,organic
compounds can be verycomplex.
C C C C
Figure 1.1: An unbranched carbon chain