1. Compounds
Unit 2 Topic 2

2. Chemical Formula
A chemical formula represents the number of each type of element bonded together in a compound.
The number of capital letters indicates how many types of elements are present (each element has only one capital letter).

3. Subscripts
A subscript directly after an element’s symbol indicates how many of that element there is in the compound (if there is no subscript then there is only one of that element).
H2O
Subscript indicates 2 Hydrogen atoms

4. Symbol
If the symbol of a compound contains parentheses, then the subscript outside the parentheses is multiplied by each element inside the parentheses.
This information is used to determine the number of each type of element in the compound. You will need to be able to do this proficiently before you learn how to add up molecular masses.

5. Examples
Calcium Phosphate
Ca – 3
P -- 2
O -- 8

6. Examples
Ammonium Carbonate
N – 2
H – 8
C – 1
O – 3
Total = 14

9. Dimensional Analysis Calculate the number of smacks in one lardo
12 tolls
3 smacks
= 1 x 12 x 3 =
9 smacks
1 x 4
1 lardo
4 tolls
What do I know about lardo?
12 tolls = 1 lardo
8 lardos = 7 fleas
4 tolls = 3 smacks
Will either of these help me get to smacks?

11. Dimensional Analysis Calculate the number of moles in 7.7 g Na
= x 1 =
0.33 moles
22.99 grams
22.99
What do I know about Na?
1 mole Na = g
Will this help me get to grams?

12. In your spiral: Label this 2.2
2 moles of CaF2 = ? Grams
1 mole of CaF2 = grams
2 moles x grams =
1 mole
Calculator: 2 moles x (78.06/1) =
grams

13. 2.2 continued 243.18 grams of CaF2 = ? moles
1 mole of CaF2 = grams
grams x mole =
78.06 grams
Calculator: x (1 / 78.06) =
3 moles

14. More problems 4 moles of Be(OH)2 = ? Grams
86 grams of Be(OH)2 = ? moles
0.25 moles of Ba(NO2)2 = ? Grams
grams of Ba(NO2)2 = ? moles