Good morning and welcome to Chemistry. Today, we will talk a bit more about the mole. I sent you chapter 10 notes a couple of weeks ago. See if you can still find them.

A mole is Avogadro’s number of things, usually particles like atoms or molecules. These two particles are so small, you have to have a LOT of them to measure their masses on a balance. Avogadro’s Number, NA, is 6.02 x 10²³
So 2 moles of iron atoms is 2 x NA or 1.204 x 10²⁴

We can also use the Periodic Table with the mole. Let’s look at iron, Fe, again.

Iron is element number 26 on the periodic table. It has a number, usually underneath the symbol, Fe, that is a decimal. The mass of one atom of iron is 55.847 amu (atomic mass units). This isn’t very useful, since it is so small, so we have converted these masses to grams for each mole of the substance. So now, one mole of iron is 55.847 grams. If you have 2 moles it is 55.847 x 2 = 112 grams (using 3 sig figs usually).

You can convert from grams to atoms or atoms to grams by converting to moles first.

Today’s questions will require a calculator (your phone is fine for homework, but not a test or quiz) and a periodic table.

1. Find tin on the periodic table. How many atoms of tin are in 17.3 moles of tin?
2. How many grams of Sn are in 34.5 moles of Sn?
3. How many grams of Sn are in 3.05 x 10²⁹ atoms of tin?

Please do your work on paper, showing ALL of your work. Take a photo with your phone and send it to me via Remind. Do this today, please.

Thank you,

Stay healthy and stay Breezy!

T. Brown