One of the difference between living organism and non living one is that their chemical composition.
A living organisim consist largely of compound of carbon, plus water. (about 55% to 65% of most animal, and 90% or more of most plant is water.)
The carbon compound of which organisim are made are called organic compounds. Organic molecules are larger and more complex in structure than most inorganic molecules. This is partly because when carbon atoms combine they tend to form either long chain or ring
Inorganic molecules are those which makes up the non-living world for example, Water, the gas of the air, and the mineral in rocks.
In addition to carbon, hydrogen, oxygen and nitrogen are common constituents of organic compounds, sometimes other elements are present. These include phosphorus, sulphur and certain metals such as iron and magnesium.
Organisms also contain small amount of minerals salt. A mineral salt is an organic substance usually found in rocks, the soil or the sea sodium chloride (common salt) is an example. The mineral salt of plant are discussed in Biology very well and those of animal too
Most of organic compound found in living things belonging to on of three main group namely the carbohydrates (starches and sugar) lipids (fats and oil) and proteins.
CHEMICAL TERMS EXPLAINED
the following definition refers to how the terms are used in this book only more comprehensive definition can be found in chemical textbooks.
A chemical substance is either an element or a compound. There are just over 100 element but many thousands of compounds.
An element is a substance which cannot be split into simpler substance by chemical means carbon, hydrogen, oxygen, and nitrogen, are simple examples.
A compound is a substance made of two or more elements Combined chemically. It's properties are different from those of it element a compound can be split into simpler substance by chemical means. water, carbon dioxide and glucose are examples of compounds.
An atom is the smallest partixls particle of an element which can take part in chemical reaction. All compounds can take part in a chemical reaction. All compounds and some element Eg oxygen hydrogen exist as two or more atoms combined together. These groups of atom are called molecules.
In chemical reaction, compound and/or elements react with each other to form one or more new substance for example when charcoal which is a form of carbon is burnt in air the carbon combines with oxygen in the air to form the gas carbon dioxide chemists represent each element by a symbol for example
C= carbon
H= hydrogen
O= oxygen
Na = sodium
Cl= chlorine
The symbol are used in chemical formulas and chemical equations.
A chemical formula represent one molecule of an element or compund it tells us the type and number of atoms in the molecule. For Example CO² means that carbon dioxide molecules consists of one atom of carbon and two atoms of oxygen.
C6H12O6 means that a glucose molecule consist of six atoms of carbon twelve atoms of hydrogen and six atoms of oxygen
A chemical equation represent a chemical reaction. For example
I) C + 02-----> CO2
Carbon oxygen carbon dioxide
Ii) 6co² + 6H2O----> C6H12O6 + 6O2
this tells us that six molecule of carbon dioxide react with six molecule of water to form one molecule of glucose and six molecule of oxygen
The substance which react are shown to the left of the arrow, and the new substance produced, to the right. The left- and right hand sides must balance. For example, if there are six carbon atoms on the left side of the equation, there must be a total of six carbon atoms on the right hand side.
Macromolecules
Some organic molecules consist of many smaller molecules combined to form one larger molecules. Examples are polysaccharides and protein such molecules are described as Macromolecules. A Macromolecules in which all smaller molecules are similar and joined together in the same way is called polymer
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