1. Avogadro’s Number and Molar Conversions Mole: the SI base unit used to measure the amount of a substance whose number of particles is the same as the number of atoms of carbon in exactly 12 grams of carbon-12

2. Avogadro’s number 6.022 × 1023, the number of atoms or molecules(or anything) in 1.000 mol

3. The Mole Is a Counting Unit Converting Between Amount in Moles and Number of Particles X moles ( 6.022 x 10 23 / 1 mol) = # particles of anything X particles ( 1 mol / 6.022 x 10 23 particles) = # moles

4. Molar Mass Relates Moles to Grams X particles( 1mol/6.022 x 10 23 particles)(molar mass/ 1 mol) = Y mass X mass( 6.022 x 10 23 particles/molar mass)(1 mol/ #particles) = Y mol http://imagine.wsu.edu/dates/importantdates.html

5. Relative Atomic Mass and Chemical Formulas Use a periodic table or isotopic composition data to determine the average atomic masses of elements. Infer information about a compound from its chemical formula. Determine the molar mass of a compound from its formula.

6. Average Atomic Mass and the Periodic Table Most Elements Are Mixtures of Isotopes The periodic table reports relative atomic mass a weighted average of the atomic mass of an element’s isotopes. i.e. while the atomic mass of a carbon-12 atom is exactly 12 amu, any carbon sample will include enough carbon-13 atoms that the average mass of a carbon atom is 12.0107 amu

7. Calculate the average atomic mass for gallium if 60.00% of its atoms have a mass of 68.926 amu and 40.00% have a mass of 70.925 amu. (.60 x 68.926amu) + (.40 x 70.925amu) = relative atomic mass

8. Chemical Formulas and Moles Formulas Express Composition

9. Hexachloroethane

10. formula C 2 Cl 6 Draw it Formulas for covalent compounds show both the elements and the number of atoms of each element in a molecule

11. Ionic compounds aren’t found as molecules, so their formulas do not show numbers of atoms. Instead, the formula shows the simplest ratio of cations and anions. CaCl 2 NaBr

12. Formulas Give Ratios of Polyatomic Ions the formula KNO 3 indicates a ratio of one K + cation to one NO 3 − anion.

13. Formulas Are Used to Calculate Molar Masses For example, the molar mass of Br 2 molecules is two times the molar mass of Br atoms (2 × 79.90 g/mol = 159.80 g/mol). Hexachloroethane g/mol = ?