Chemical
Compounds
What is a COMPOUND?
A substance composed of two or more
elements that have been chemically united.
What is a CHEMICAL FORMULA?
A way of expressing the atoms that make
up a compound
Number of Atoms in a Compound
Please collect the number of atoms in a compound
worksheet from the front of the room
Note: just do the first page, if you need extra practice
do the back!
Molecular Mass
Sum of the atomic mass of each element that makes up the
compound.
Unit = Unified atomic mass unit = One Proton OR One Neutron
• Example:
H2O
= (2 x H) + (1 x O)
= (2 x 1u) + (1 x 16u) = 18u
NOTE: WE ARE NOT INTERESTED IN MOLECULAR MASS! We can’t weigh
individual Molecules!
Molar Mass - Our second NEW Unit Converter
• The mass of one mole of a particular
Molecule!
• Expressed as either….
grams
mol
OR
mol
grams
Example:
Example:
What is the molar mass of NaCl?
• # of Na atoms =
____________
• Atomic mass of Na =
____________
• # of Cl atoms =
____________
• Atomic mass of Cl =
____________
What is the molar mass of H2O?
• # of H atoms =
____________
• Atomic mass of H =
____________
• # of O atoms =
____________
• Atomic mass of o =
____________
• Molar mass =
•
____________
Molar mass =
____________
Remember…
Molar Mass is a unit converter
• It allows us to convert from…..
grams  mols or mols  gram
• It’s units are g/mol or mol/g
Your Turn!
• Complete the two questions (from your notes) below!
The Mole Wheel
Please keep this at the FRONT of your binders
Note: We don’t have all the tools to use this yet,
but as we move forward this will become more
and more useful
Homework
Mole Crunching!
Please collect the worksheet from the front of the room!
Note: there is an EXTRA worksheet on my website if you
need extra help!