Chemical Symbols and Chemical Symbols and FormulasFormulas

Chemical SymbolsChemical Symbols All All elementselements in the in the Periodic TablePeriodic Table have have

symbols that are symbols that are recognized recognized world wideworld wide.. It does not matter which It does not matter which countrycountry you you

are in or the are in or the languagelanguage you speak. you speak. Example:Example: The element The element IronIron is always is always

identified by “identified by “FeFe” and ” and OxygenOxygen is “ is “OO”.”. The names are not always the same but The names are not always the same but

the symbols are. “the symbols are. “FeFe” is ” is iron in Canadairon in Canada, , fer in Francefer in France and and fier in Romaniafier in Romania..

Chemical SymbolsChemical Symbols

A A Chemical symbolChemical symbol is is an abbreviation of an abbreviation of a name of an a name of an element.element.

Capital letter if only Capital letter if only one letter.one letter.

Only first letter Only first letter capital if more than capital if more than one letterone letter

ElementElement Chemical Chemical SymbolSymbol

OxygenOxygen OO

NitrogenNitrogen NN

HydrogenHydrogen HH

SodiumSodium NaNa

SodiumSodium comes from the word comes from the word sodanum, a headache remedy, and sodanum, a headache remedy, and it’s symbol (it’s symbol (NaNa) comes from the Latin ) comes from the Latin word word NaNatrium.trium.

Chemical FormulasChemical FormulasA A chemical formulachemical formula is the combination is the combination

of symbols that represent a of symbols that represent a particular compound.particular compound.

The chemical formula indicates which The chemical formula indicates which elements are present in the elements are present in the compound and in what proportions.compound and in what proportions.

Ex. 1: Ex. 1: Water moleculeWater molecule

HH22OO: : 2 atoms of hydrogen, 1 atom of 2 atoms of hydrogen, 1 atom of oxygenoxygen

Ex. 2: Ex. 2: Iron Oxide moleculeIron Oxide molecule

FeFe22OO33: : 2 atoms of iron, 3 atom of oxygen2 atoms of iron, 3 atom of oxygen

Chemical Formulas - Chemical Formulas - ExamplesExamples

Calcium Carbonate (chalk) – CaCOCalcium Carbonate (chalk) – CaCO33

Sodium Chloride (salt) – NaClSodium Chloride (salt) – NaCl Acetysalicylic acid (aspirin) – CAcetysalicylic acid (aspirin) – C99HH44OO88

Acetic acid (vinegar) – CAcetic acid (vinegar) – C22HH44OO22

Chemical FormulasChemical Formulas

NOTESNOTES::

- Each - Each symbolsymbol in a in a formulaformula represents an represents an element.element.

- If only - If only one atomone atom of an element is present of an element is present in the compound, in the compound, nono subscript is used. subscript is used.

- If - If more than one atommore than one atom of an element is of an element is used, then the symbol is used, then the symbol is followed by a followed by a number indicating how many atoms are number indicating how many atoms are usedused. This is called the . This is called the subscript.subscript.

1 atom of sodium

2 atoms of hydrogen (in a hydrogen molecule)

3 atoms of magnesium2 atoms of phosphorus8 atoms of oxygen 13 total atoms

3 carbon atoms