1. Chemical Formulas Everyday Examples
Everything has a chemical formula
In this lesson we are going to learn about chemical formulas but before we continue I would like to show you some everyday examples of things that you might like so that you can understand that everything that is matter has a chemical formula. Takis, underneath the picture you can see it’s CF, Gatorade in another example and body lotion, if the people that make these everyday products don’t include the right elements then we can suffer the consequences like getting sick of in the case of body lotion it can burn our skin.

2. Chemical Formulas
Tells you the different elements and how many atoms are in a molecule
CF tells you the different elements and how many atoms are in a molecule. Remember a molecule is 2 or more atoms joined together, as you can see in the picture we have 2 molecules of water. Each of the molecules have 2 gray color elements that represent the hydrogen atoms joined with the red atom that represents the oxygen

3. Parts of a Chemical Formula
Chemical symbols tell what elements are in the molecule
The chemical symbols are telling us what elements are present. The capitalized H is the symbol for hydrogen and the capitalized O is the symbol for Oxygen.

4. A note about Chemical Symbols
Each element is represented by a one or two letter chemical symbol.
First letters of chemical symbols are capitalized.
When a second letter is used, it is lowercase.
As I mentioned in the previous slide the symbols represent a particular element of the PT. In the bottom you can small section of a PT with different elements.

5. Parts of a Chemical Formula
Subscripts small #s, tell how many atoms of a certain element. No subscript = 1
So you are pretty much are just counting the letter in other words a single letter = 1.

6. Parts of a Chemical Formula
Coefficients big #s, tell how many molecules there are. No coefficient= 1
In this particular example we have 2 water molecules in the picture hence the #2 in front of the chemical formula

7. 2H2O 1 Example Chemical Symbol Coefficient Subscript
In this slide you have it all together coefficient tells you how many molecules, chemical symbols tell you the elements present in the formula and subscripts the small # tells you how many atoms of that particular element, if the symbol its with out any subscript is = 1
Subscript

8. MgCl2 Atoms of Magnesium: Atoms of Chlorine: Total atoms
LET’S PRACTICE!
MgCl2 Atoms of Magnesium: Atoms of Chlorine: Total atoms 1 2 3
Let’s practice, in this CF we have 2 different elements and we need to count the atoms. Atoms of Mg =1 and atoms of Cl =2, the total atoms are 3. In the next slide you will see a MC question with a similar practice, after you count the atoms choose the correct answer

9. Al2S3

10. LET’S PRACTICE!
H2SOH4 Atoms of Hydrogen: Atoms of Sulfur: Atoms of Oxygen: Total atoms: 6 1 4 11
In this other practice we have to pay attention that the H repeats, so that means that I have to add up all the hydrogens and the total is 6, S =1, O=4 and the total atoms in the CF is 11

11. CH3OH

12. THIS COULD BE A LITTLE TRICKY…
Ca3(PO4)2 Atoms of Calcium: Atoms of Phosphorus: Atoms of Oxygen: Total atoms: 3 2 8 13
This could be a little tricky because I have a parenthesis and everything inside the parenthesis I have to multiply by the subscript outside. The Ca atoms are 3, calcium is outside of the parenthesis so you don’t need to multiply but P is inside so I will multiply by the subscript 2 and that gives me 2 P and I do the same for the O which gives me 8 after multiplying by the subscript. When I add up all the atoms in the CF they add up to 13. In the next slide you will have a very similar problem and you will need to write the symbol and amount of atoms for that element

13. Al2(SO4)3

14. What about this BAD BOY???
2Ca3(PO4)2 Atoms of Calcium: Atoms of Phosphorus: Atoms of Oxygen: Total atoms 6 4 16 26
This is the hardest problem because we not only have parenthesis but we have a coefficient 2, don’t sweat too much its really not that hard, however remember the coefficient needs to be multiply by everything including the parenthesis, what I mean is the 2 multiplies with the Ca for a total of 6 then the 2 is multiplied by the P inside the parenthesis and by the subscript for a total of 4 P, I do the same for the O 2 times 4 =8 and 8 times 2 = 16 for the O atoms. Add them all together and you have 26 total atoms. A similar problem is waiting for you next slide good luck.

15. 3Si2(CH2)4