The document reviews key concepts for the third quarter assessment including the scientific method, bonding, naming compounds and ions, mixtures, the mole, energy diagrams, phases of matter, reaction rates, and gas laws. It provides examples and explanations of important terms and concepts to help students prepare.

1. Third Quarter Assessment
Review Material

2. The Scientific Method
• Scientists are always faced with the task of properly
designing an experiment to test any and all variables.
– Example: You decide to test what happens to a balloon when
placed in a warm environment (like a moderately hot oven)
versus what happens to a balloon placed in a cold environment
(like the freezer).
• Several important key terms in designing an experiment:
– Constants - The variables that never change in the experiment.
• Ex: The size of the balloon, the type of balloon, etc.
– Control - The "normal" in an experiment. This is usually what you compare your experiment
to.
• Ex: A balloon placed at room temperature.
– Independent Variable – The variable that you directly control.
• Ex: Where you placed the balloon (oven or freezer).
– Dependent Variable – The variable that changes because of the independent variable.
• Ex: The size of the balloon

3. Covalent vs. Ionic Bonds
• Know the difference between covalent and
ionic bonds.
– Covalent bonds are always between a non-metal
and a non-metal. (groups 4-7)
• Ex: CCl4
• These are ALWAYS referred to as molecules.
– Ionic bonds are always between a metal with a
non-metal. (groups 1-3 with groups 4-7)
• Ex: LiF
• These are usually referred to as compounds.

4. Naming Ionic Bonds
• Name the cation first and the anion second.
• Change the ending of the anion to –ide.
– Ex: Name MgCl2
• Cation: Mg+2 magnesium
• Anion: Cl-1 chloride
– So the name is magnesium chloride
• Note: You don’t have to worry about the
subscripts. BUT MAKE SURE YOUR
CHARGES= “0”
• Do not forget your polyatomic ions.

5. Naming Covalent Molecules
– 1: mono- • Covalent molecules are named in a
– 2: di- similar fashion, except you must use
– 3: tri- the prefixes you learned in class.
– 4: tetra-
– 5: penta- • Name the element as is placing the
– 6: hexa- prefixes for the subscripts and change
– 7: hepta- the ending to –ide.
– 8: octa- – C4H10
– 9: nona- • Tetracarbon decahydride
– 10: deca- – NO2
• Nitrogen Dioxide

6. Mixtures
• Mixtures are • Filtration
combinations of
substances that retain • Distillation
their physical and
chemical properties.
• You can separate • Chromatography
mixtures by using
different techniques. • Crystallization
• See if you can
remember these
separation techniques:

7. The Mole
• The mole is the SI unit used to measure the
amount of a substance.
• You should be able to convert back and forth
between atoms, moles, and grams.
• You should be able to do this for elements and
for compounds.
• Remember this roadmap:
Atoms moles mass (g)

8. Energy Diagrams
• Energy diagrams show
phase changes for a
molecule.
• These phase changes
occur as a result of the
relationship between
temperature and energy.
• Look at the diagram at
the left and think of
water and its phase
changes.

9. Phase changes
• Phase changes occur
wherever there is a flat
region in the diagram.
• What happens to the
molecules as you increase
the temperature?
• Think of the three states
of matter and what
happens to the molecules
in these states.

10. Phases and Their Energies
• As you increase the
temperature, molecules
gain more energy and
break their attraction.
• Look at the picture to
the right to help you
visualize the concept.

11. Reaction Rates
• Chemists can increase the rate of reactions by
doing one of several things:
– Increase the temperature of the substance
– Agitate the mixture
– Increase the surface area of a substance
– Decrease the volume of the container
– Increase the pressure of the container

12. Reaction Rates
• Reaction rates are related to the amount of collisions.
• Temperature: As you increase the temperature,
molecules move faster and collide more often.
• Agitation: You are causing the molecules to collide as
you mix them.
• Increasing the surface area: Allows for more
collisions to occur due to more space for them to occur.
• Decreasing the volume of the container: There is less
room for the molecules to move apart so they’ll run into
each other more often.
• Increasing the pressure: Molecules are more likely to
collide.

13. Gas Laws
• In order to solve any gas problems, you must
remember the following equation:
– PV = nRT
• P = pressure
• V = volume
• n = number of moles
• R = a constant and must be given
• T = temperature