1. Topic: Formula Mass Write the chemical formula based on the structural formula below C2H6O2C2H6O2

2. Formula mass of an element formula mass of element = to atomic mass –But units change from amu to grams

3. Formula mass of elements (p.1 in packet) Zinc: –atomic mass of 65.409 amu so formula mass = 65grams Nitrogen: –atomic mass of 14.0067 amu so formula mass = 14 grams Neon: –atomic mass of 20.190 amu so formula mass = 20 grams

4. Formula Mass of Compounds = sum of masses of atoms in formula Round atomic masses to whole number Step 1 count atoms Step 2 look up mass Step 3 multiply Step 3 add Ex: H 2 O H = 2 O = 1 x 1 x 16 = 2 = 16 18 g

5. Formula Mass of Compounds Try CH 4 C = 1 X 12 = 12 H = 4 X 1 = 4 Sum = 16 g

6. Formula Mass for Al(NO 3 ) 3 Al(NO 3 ) 3 Al = 1 N = 1 X 3 = 3 O = 3 X 3 = 9 Al = 1 x 27 = 27 N = 3 x 14 = 42 O = 9 x 16 = 144 213 g