Because It is usually derived from the name of the element.
Chemical symbols. Each element is given its own chemical symbol, like O for oxygen and Cl for chlorine. Chemical symbols are usually one or two letters long, but sometimes three letters are used. Every chemical symbol starts with a capital letter, with the second or third letters written in lower case. For example, Mg is the correct symbol for magnesium, but mg, mG and MG are wrong. List of elements by symbol. 189 pages on this wiki. This is a list of chemical elements by symbol, including the current symbols used to identify the chemical elements as recognized by the International Union of Pure and Applied Chemistry, as well as proposed and historical symbols.  In chemistry, a symbol is a code for a chemical element. It is usually derived from the name of the element, often in Latin. This is an example of an atomic symbol. The text boxes explain where the numbers are derived from. Chemical symbols may be modified by the use of prepended superscripts or subscripts to specify a particular isotope of an atom. Additionally, appended superscripts may be used to indicate the ionization or oxidation state of an element. Air does not have a chemical formula because air is neither an element nor a chemical compound. Air is mixture of Oxygen (element), carbon dioxide (chemical compound), nitroge … n (element), and water as humidity (chemical compound). For example, the water molecule is made of two atoms of Hydrogen and one atom of Oxyg … en; therefore its chemical formula will be H2O, where H and O are the symbols of the elements involved and the 2 is a subscript, telling how many atoms are present of the element preceding it. For example, He is the symbol for helium (English name, not known in ancient Roman times), Pb for lead (plumbum in Latin), W for tungsten (wolfram in German, not known in Roman times). Only the first letter is capitalized. Chemical symbols may be modified by the use of prepended superscripts or subscripts to specify a particular isotope of an atom. Additionally, appended superscripts may be used to indicate the ionization or oxidation state of an element. It is important for scientists around the world to agree on the  names and chemical symbols of the elements so that all scientists  around the world all know what they are t … alking about. For example, the water molecule is made of two atoms of Hydrogen and one atom of Oxyg … en; therefore its chemical formula will be H2O, where H and O are the symbols of the elements involved and the 2 is a subscript, telling how many atoms are present of the element preceding it. Other elements have symbols that don't seem to relate to their names at all! For these elements, the symbol usually refers to an older element name that isn't used any more. Here's an alphabetical list of element symbols with the corresponding element name. Keep in mind that the names for the elements (and their symbols) may be different in languages other than English. By Anne Marie Helmenstine, Ph.D A chemical symbol for an element is one or two letters. These are found on the periodic table of elements. The chemical symbol is an abbreviation of the chemical element name. … Example: O is the chemical symbol for Oxygen. K is the chemical symbol for Potassium. Pb is the symbol for lead. He is the symbol for helium. It is important for scientists around the world to agree on the  names and chemical symbols of the elements so that all scientists  around the world all know what they are t … alking about. If there  were different names for each elements and symbols around the world  it would confuse people A chemical formula is a notation made up of the chemical symbols of the elements present in a compound and numerical subscript that indicate the number of atoms of each element present in a molecule of the compound.. A chemical formula provides information about the atomic composition of a substance. Making error of capitalizing the second letter of an elements symbol can dramatically alter the meaning of a chemical formula. When we attempt to write a formula it is important to know whether the substance actually exists.
http://www.bbc.co.uk/bitesize/ks3/science/chemical_material_behaviour/atoms_elements/revision/3/ http://chemistry.wikia.com/wiki/List_of_elements_by_symbol https://en.wikipedia.org/wiki/Chemical_symbol http://www.answers.com/Q/Why_you_think_chemical_symbols_and_formula_are_an_important_part_of_communication_among_scientists https://en.wikipedia.org/wiki/Chemical_symbol http://www.answers.com/Q/Why_you_think_chemical_symbols_and_formula_are_an_important_part_of_communication_among_scientists http://chemistry.about.com/od/elementfacts/a/elementsymbols.htm http://www.answers.com/Q/What_is_importance_of_chemical_symbols http://formulas.tutorvista.com/chemistry/chemical-formula.html
why are chemical symbols important