SCIENCE REVIEW
TEST READINESS
Properties of Matter
 Brittleness - the property of matter that is how easily the
substance breaks or shatters when force is applied to it.
 Ductility - property of a metal in which it can be stretched
without breaking.
 Elasticity - the ability of a substance to be stretched and then to
return to its original shape.
 Hardness - property of matter that determines how easily the
substance can be scratched.
 Malleability - the property of a metal that allows it to be
hammered, rolled, pressed or forged.
HOW DOES ONE STUDY FOR A
LAB?
HOW DOES ONE STUDY FOR A
LAB?
 Practice with the tools, e.g. thermometer, scales, weighing tray,
stopwatch, calculators
 Practice making graphs, especially line graphs (x: time, y:
temperature), using data tables
 Memorize the definitions of key science words
 Use other sources for quizzing, e.g. BrainPop,
aboutChemistry.com
 Make own quiz/test
 Have a peer/parent quiz you on definitions/method
KEY WORDS: CHEMICAL
CHANGE
 Chemical change
 Endothermic reaction
 Exothermic reaction
CHALLENGE
Is cooking an example of
chemical or physical change?
Cooking
 When most of the food is cooked, it can not be reversed to
the original substance it was in before cooking it, for
example, when meat is cooked it changes the color.
chemical change
 A chemical reaction is a chemical change which forms new substances;
the starting materials (reactants) are different from the product
 When a chemical change takes place there is the change of
temperatures where there might be loss of heat but in most chemical
change reactions heat or energy is produced.
 Another characteristic of a chemical change is the change in color. For
example when an iron nail comes into contact with water, the nail
begins to rust and its color change from silver to reddish brown
meaning that chemical change has taken place.
 The production of gases and solids is also another characteristic of a
chemical change. The gases produced appear in the form of bubbles as
a result of the reaction. A solid maybe formed and it separates itself
from the solution after the reaction.
BrainPop Movie
 http://www.brainpop.com/science/matterandchemistry/pr
opertychanges/preview.weml
Endothermic reaction
 An endothermic reaction is any chemical reaction that absorbs
heat from its environment. It is a reaction that requires energy to
proceed. The intake of energy may be observed as a decrease in
temperature as the reaction proceeds. Once the reaction is
complete, the temperature of the mixture will return to room
temperature.
 Examples
1.
2. reacting ethanoic acid with sodium carbonate
3. photosynthesis (chlorophyll is used to react carbon dioxide plus
water plus energy to make glucose and oxygen)
Exothermic reaction
 Many chemical reactions release energy in the form of heat, light,
or sound. These are exothermic reactions.
 Exothermic chemical reactions produce heat.
 Examples
1. In this reaction vinegar is used to remove the protective coating
from steel wool, allowing it to rust. When the iron combines with
oxygen, heat is released.
Collecting Data
Endothermic
Exothermic
Initial Temperature
°C
°C
Final Temperature
°C
°C
Temperature change
rate
Graphing rate of reaction
Law of
Conservation
of Mass
CHALLENGE: EXPLAIN
WITH EXAMPLE
Law of Conservation of Mass
 the mass of substances produced (products) by a chemical
reaction is always equal to the mass of the reacting
substances (reactants).
 in a chemical reaction, the mass of the products equals the
mass of the reactants.
 Example
1.00g carbon + 5.34g sulphur
6.34g carbon disulphide
Key words: Physical Change
 Boiling point
 Melting point
 Sublimation
 Deposition
 Freezing
 Evaporation
 Filtration
Changes in States of Matter
Deposition
Evaporation
Freezing
Melting
Sublimation
The Water Profile
Boiling point
 temperature at which a liquid changes to a gas
Melting point
 the temperature at which a substance changes from a
solid to a liquid.
sublimation
 the changing of a gas directly to a solid
evaporation
 changing of a liquid to a vapor at any temperature below
its boiling point.
Salt on snow-covered roads?
 If you live in an area with a cold and icy winter, you have
probably experienced salt on sidewalks and roads, used to
melt the ice and snow and keep it from refreezing.
 Salt is also used to make homemade ice cream.
 In both cases, the salt works by lowering the melting or
freezing point of water. The effect is termed 'freezing point
depression'. ”
 So, when you add a salt to ice with a little bit of water, the salt
lowers the freezing point of the water, keeping it from refreezing as easily and helping to melt the rest of the ice.
Pressure Cooker Visualizer
Ms Peters cooks rice in a pressure
cooker. Why?
 A pressure cooker is a sealed pot.
 Steam trapped inside the pot under pressure allows the
temperature to rise beyond what it could reach normally in a
traditional uncovered pot.
 As the pressure inside the cooker increases, the boiling point of
the water inside increases as well. This causes the food to cook at
a higher temperature, which cooks it faster.
CHEMICAL CHANGE
PHYSICAL CHANGE
In a chemical change where there is a
chemical reaction, a new substance is
formed and energy is either given off or
absorbed.
A physical change in a substance doesn't
change what the substance is.
If a piece of paper is burned, it is broken up
into different substances that are not paper.
For example, if a piece of paper is cut up into
small pieces it still is paper. This would be a
physical change in the shape and size of the
paper.
Chemical changes cannot be reversed with
the substance changed back without
extraordinary means, if at all.
Physical changes can be reversed.
If one made a recipe for a cake with flour,
water, sugar and other ingredients and
baked them together, it would take
extraordinary means to separate the various
ingredients out to their original form.
If one decided to mix sugar into water to
make sugar water, this would be a physical
change as the water could be left out to
evaporate and the sugar crystals would
remain.
GOOD LUCK!