1. Chemical Symbols and Formulas

2. Chemical Symbols  All elements in the Periodic Table have symbols that are recognized world wide.  It does not matter which country you are in or the language you speak.  Example: The element Iron is always identified by “Fe” and Oxygen is “O”.  The names are not always the same but the symbols are. “Fe” is iron in Canada, fer in France and fier in Romania.

3. Chemical Symbols A Chemical symbol is an abbreviation of a name of an element. Capital letter if only one letter. Only first letter capital if more than one letter Element Chemical Symbol OxygenO NitrogenN HydrogenH SodiumNa

4. Sodium comes from the word sodanum, a headache remedy, and it’s symbol (Na) comes from the Latin word Natrium.

5. Chemical Formulas A chemical formula is the combination of symbols that represent a particular compound. The chemical formula indicates which elements are present in the compound and in what proportions. Ex. 1: Water molecule H 2 O: 2 atoms of hydrogen, 1 atom of oxygen Ex. 2: Iron Oxide molecule Fe 2 O 3 : 2 atoms of iron, 3 atom of oxygen

6. Chemical Formulas - Examples  Calcium Carbonate (chalk) – CaCO 3  Sodium Chloride (salt) – NaCl  Acetysalicylic acid (aspirin) – C 9 H 4 O 8  Acetic acid (vinegar) – C 2 H 4 O 2 

7. Chemical Formulas  NOTES: - Each symbol in a formula represents an element. - Each symbol in a formula represents an element. - If only one atom of an element is present in the compound, no subscript is used. - If only one atom of an element is present in the compound, no subscript is used. - If more than one atom of an element is used, then the symbol is followed by a number indicating how many atoms are used. This is called the subscript. - If more than one atom of an element is used, then the symbol is followed by a number indicating how many atoms are used. This is called the subscript.

9. 1 atom of sodium 2 atoms of hydrogen (in a hydrogen molecule) 3 atoms of magnesium 2 atoms of phosphorus 8 atoms of oxygen 13 total atoms 3 carbon atoms