1. How We Can Accurately Measure Atoms
The Mole
How We Can Accurately Measure Atoms

2. Remember the Mass of an Atom
An AMU stands for atomic mass unit.
The AMU for any element or molecule is found by simply using the average mass value from the p. table
The AMU for carbon is
The AMU for Boron is

3. What is a Mole?
Just like a dozen means 12 and a couple means two, the mole is an exact number of something
We use the mole because atoms are so small, it would be too difficult to work in quantities so high

4. Avogadro’s number
In honor of Amedeo Avogadro di Quaregna, this exact quantity for the mole (mol) was named after the famous scientist
So how much is a mole you ask?

5. Memorize it
6.02 x 1023

6. So What’s This All Mean
If you measure 31g of phosphorous, you have one mole of phosphorous.
If you measure 32g of sulfur, you have one mole of sulfur
In both cases you measured 6.02 x 1023 atoms of each substance

7. One Step Further
If I asked for one mole of NaCl how many grams would you need?
Na = 23 and Cl = 35
1 mole of NaCl would require 58 grams of the substance
If you measure out 58g, you just measured out 6.02 x 1023 molecules

8. Gram Atomic Mass
The (gam) is the atomic mass of an element expressed in grams
(gam) values are average masses rounded off one place after the decimal point

10. Gram Molecular Mass (gmm)
Same concept as (gam) except we are dealing in compounds
1 mole of SO3 has a mass of 80.1 g

11. Gram Formula Mass (gfm) Formula mass expressed in grams
Ammonium carbonate
((NH4)2CO3)
[14 + (1 x 4)] (16 x 3)
gfm of ammonium carbonate is 96g