Counting Atoms in a Chemical Formula

Open your science notebook to the next available page and title it "Counting Atoms." Having these notes is going to be VERY helpful when doing your practice work.

• Yes, I have titled my paper and am ready to take notes!

• No, I do not have paper or something to write with.

Did you write the title, chemical formula H₂O, and the E/A chart?

• Yes.  I also know I can pause the video if it's going to fast for me to write.

• No, I'll do it now.  I know I can pause the video if it's going too fast for me to write, and I can rewind and rewatch anything I missed.

• No, and I don't plan to write it down, either.

How many atoms are there when there is no subscript? (In this case, how many atoms of oxygen are present?)

• 0

• 1

• 2

Complete the whole EA chart for CH₄.

How many TOTAL elements are present?

• 1

• 2

• 4

• 5

How many carbon atoms are in CH₄?

• 0

• 1

• 4

How many hydrogen atoms are in CH₄?

• 0

• 1

• 4

• 5

What is the total number of ATOMS in CH_4?

• 1

• 2

• 4

• 5

List the elements for (Al₂SO₄)₃ in your E/A chart.  The first element is aluminum, with a chemical symbol Al (the "l" is a lowercase L).  How many TOAL ELEMENTS are present in this molecule?

• 2

• 3

• 4

Which elements will be multiplied by 3 in Al₂(SO₄)₃?

• Al, S, O

• S, O

Which elements will be multiplied by 2 in Sr₃(PO₄)₂?

• Sr, P, O

• P, O