1. Chemical Compounds

2. What is a COMPOUND? A substance composed of two or more elements that have been chemically united.

3. What is a CHEMICAL FORMULA? A way of expressing the atoms that make up a compound

4. Number of Atoms in a Compound Please collect the number of atoms in a compound worksheet from the front of the room Note : just do the first page, if you need extra practice do the back!

5. Molecular Mass Sum of the atomic mass of each element that makes up the compound. Unit = Unified atomic mass unit = One Proton OR One Neutron Example: H2OH2O  = (2 x H) + (1 x O)  = (2 x 1u) + (1 x 16u) = 18u NOTE: WE ARE NOT INTERESTED IN MOLECULAR MASS! We can’t weigh individual Molecules!

6. Molar Mass - Our second NEW Unit Converter The mass of one mole of a particular Molecule! Expressed as either….

7. Example: What is the molar mass of NaCl? # of Na atoms =____________ Atomic mass of Na =____________ # of Cl atoms =____________ Atomic mass of Cl = ____________ Molar mass =____________ Example: What is the molar mass of H 2 O? # of H atoms = ____________ Atomic mass of H = ____________ # of O atoms = ____________ Atomic mass of o = ____________ Molar mass = ____________

8. Remember… Molar Mass is a unit converter It allows us to convert from….. grams  mols or mols  gram It’s units are g/mol or mol/g

9. Your Turn! Complete the two questions (from your notes) below!

10. The Mole Wheel Please keep this at the FRONT of your binders Note: We don’t have all the tools to use this yet, but as we move forward this will become more and more useful

11. Homework Mole Crunching! Please collect the worksheet from the front of the room! Note: there is an EXTRA worksheet on my website if you need extra help!