1. 7.5.5 Translate chemical symbols and the chemical formulas of common substances to show the component parts of the substances

2. Chemical Symbols  Chemical symbols show the ATOMS of the elements composing a substance  Symbols are written with ONE, TWO, or THREE letters  The first letter is always CAPITALIZED  Each element has a different symbol

3. You need to memorize this: ElementSymbol SodiumNa ChlorineCl HydrogenH OxygenO CarbonC NitrogenN

4. Element VS. Compound  Elements are made up of ONE kind of atom  The symbol for each element is unique  Compounds are composed of TWO or more elements  Their formulas have more than one type of symbol to show the different elements that make up the compound

5. Chemical Formulas  A chemical formula is constructed from the symbols of the elements composing the substance  The numbers, known as SUBSCRIPTS, show how many of each kind of atom are in the compound  The subscript is written to the lower right of the element symbol  Example: H 2 O

6. More about Chemical Formulas  If no subscript is written then only ONE atom of that element is part of the compound  Example: H 2 O  Hydrogen—two hydrogen atoms  Oxygen– one oxygen atom

7. Chemical Formulas to Memorize CompoundSymbol WaterH2OH2O Table SaltNaCl Simple Sugar (Glucose)C 6 H 12 O 6 Oxygen GasO2O2 Carbon DioxideCO 2 Nitrogen GasN2N2