The Periodic Table and the Mole

The Periodic Table and the Mole

As we have learned, the mass number on the periodic table represents the mass of one mole (6.02 x 1023) of that element. For example, one mole of titanium (element 22) weighs 47.867 grams. Therefore, 48.867 grams of titanium contains 6.02 x 1023 atoms of titanium.

For compounds (substances with 2 or more different atoms bonded together like H2O), the sum of the masses of all the atoms in the compound represents one mole of the compound. For example, the sum of the masses of the elements in H2O is 18.015 grams (2 x 1.0079 + 15.999). If you hold 18.015 grams of water in your hand or mouth, you are holding 6.02 x 1023 H2Os. That’s 602,000,000,000,000,000,000,000 H2Os.

The Lab

For each station, bring me the following:

1. One mole of aluminum

2. 6.02 x 1023 atoms of iron

3. One mole of table salt, NaCl

4. 6.02 x 1022 molecules of sucrose (table sugar), C12H22O11

5. Half of a mole (3.01 x 1023) of water

6. 0.250 mole of Na3PO4

Lab Questions

1. Why do chemists use the quantity called a mole? Why not talk about individual atoms?

2. See the data below:

32.065 grams of sulfur contains 6.02 x 1023 (602,200,000,000,000,000,000,000) atoms of sulfur.

3.2065 grams of sulfur contains 6.02 x 1022 (60,220,000,000,000,000,000,000) atoms of sulfur.

0.32065 grams of sulfur contains 6.02 x 1021 (6,022,000,000,000,000,000,000) atoms of sulfur.

0.0032065 grams of sulfur contains 6.02 x 1020 (602,200,000,000,000,000,000) atoms of sulfur.

Given this data, how would you describe the size of one atom?

3. A bottle of Dasani water contains 20 oz. of water. This is the same as 591 mL. This is the same as 591 g. If a mole of water weighs about 18 g, how many moles are in the bottle? Using the answer above, if you drink the whole bottle, how many molecules would you drink? How is it possible to drink this many molecules?