Moles, Molecules and Grams

A quick review!

National Mole Day

October 23rd from 6:02 a.m. to 6:02 p.m.

National Mole Day is celebrated around the world to engage young minds in the study of chemistry.

Established by a high school chemistry teacher, Maurice Oehler, in 1991.

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 6.02 x 1023 molecules in a mole:

=

Example: #12 from your worksheet

How many grams are there in 1 x 1024 molecules of BCl3?

1)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