Moles, Molecules and Grams A quick review!

National Mole Day October 23rd from 6:02 a.m. to 6:02 p.m. Established by a high school chemistry teacher, Maurice Oehler, in 1991. National Mole Day is celebrated around the world to engage young minds in the study of chemistry.

Amedeo Avogadro 6.02 x 1023

Things to understand about Avogadro's number • It is a huge number, far greater in magnitude than we can visualize. • Its practical use is limited to counting tiny things like atoms, molecules, "formula units", electrons, or photons. • It is a number, just like a "dozen", and thus is dimensionless; you can think of Avogadro's number as the "chemist's dozen".

There are 12 eggs in a dozen: 12 eggs = There are 6 There are 12 eggs in a dozen: 12 eggs = There are 6.02 x 1023 molecules in a mole: =

Example: #12 from your worksheet How many grams are there in 1 x 1024 molecules of BCl3? Find the molar mass of BCl3 1 x B atom: 1 x 10.811 = 10.811 3 x Cl atoms: 3 x 35.453 = 106.359 117.17 g/mol

Example: #12 from your worksheet How many grams are there in 1 x 1024 molecules of BCl3? 2) Set up your conversions 1 x 1024 molecules x 1 mole x 117.17 grams of BCl3 6.02 x 1023 molecules 1 mole

Example: #12 from your worksheet How many grams are there in 1 x 1024 molecules of BCl3? 3) Do your calculations and cross off your units 1 x 1024 molecules x 1 mole x 117.17 grams of BCl3 6.02 x 1023 molecules 1 mole = 194.63 grams of BCl3

Conversion

Nomenclature A quick review!

Naming Binary Compounds A Metal and a Non-Metal.... Name of Metal + Non-Metal with suffix “ide” Ex: CaCl Calcium Chloride

Naming Binary Compounds A Non-Metal and a Non-Metal.... (prefix) non-metal + (prefix) non-metal with suffix “ide” Note: if the prefix of the 1st non-metal is mono, then we do NOT write it Ex: CO2 Carbon dioxide

Writing the Chemical Formula The cross over rule..... N2+ O3- N3O2