1. Aim: What is the empirical and what is the molecular formulas?
Do now: For the following compound write down number of atoms of each element and the total number of atoms CH3OCH4OCH5
Announcement: Quiz Friday

2. Formulas
Formulas - use chemical symbols and numbers to show both qualitative and quantitative information about a substance.
Qualitative - information that relates to things that cannot be measured. (ex. What elements are in the compound)
Quantitative - information that deals with things that can be either counted or measured. (ex. Number of each atom present in the compound)

3. The Empirical Formula
The lowest whole number ratio of elements in a compound.
The molecular formula the actual ratio of elements in a compound
The two can be the same.
CH2 empirical formula
C2H4 molecular formula
C3H6 molecular formula
H2O both

4. Calculating Empirical
Just find the lowest whole number ratio
C6H12O6
CH4N
It is not just the ratio of atoms, it is also the ratio of moles of atoms
In 1 mole of CO2 there is 1 mole of carbon and 2 moles of oxygen
In one molecule of CO2 there is 1 atom of C and 2 atoms of O

5. Learning Check Write the Empirical Formula for Each of the Following:
a. P4O6 _________________
b. C6H9 _________________
c. CH2OHCH2OH _________________
d. BrCl2 _________________
e. C6H8O6 _________________
f. C10H22 _________________
g. Cu2C2O4 _________________
h. Hg2F2 __________

6. How do we write chemical formulas using the elements name?
We locate the symbol of the given element
We locate the charge of the given element
We put the element symbols together
We switch the charges and make them into the subscripts

7. Learning Check Write the compound for each of the following:
Alumnium and chlorine
Carbon and four chlorines
Potassium and oxygen
Lithium and sulfur
Lithium and flourine
Calcium and arsenic
Oxygen and hydrogen
Oxygen and carbon

8. Exit slip
Put together the following elements: 1. Sr and Ge 2. K and Al 3. Li and S Tell me the charges of the following compounds: NaCO3 and NH4CO3