Physical and Chemical Changes Notes
P5.5C Chemical Properties
Chemical properties describe the way a substance reacts with other substances.
Flammability is a chemical property. It describes a substances ability to burn or catch on fire.
Corrosion is when metals combine with nonmetals from the environment. Corrosiveness is a
chemical property. Iron corrodes by rusting.
Boiling point is the temperature at which a substance boils.
Substances change from liquid to gas at their boiling point.
Freezing point is the temperature at which a substance freezes.
Substances change from a liquid to a solid at their freezing point.
P5.5C Physical and Chemical Changes
A physical change alters the form of an object without changing what type of matter it is.
Changes to size and shape are physical changes. Cutting paper, sharpening your pencil, cutting
your hair, melting ice are all examples of physical changes.
Combining 2 substances into a MIXTURE is also a physical change.
Physical changes can be reversed.
Chemical changes occur when atoms link together in NEW ways to create substances
DIFFERENT from the original substance. This produces a chemical reaction. When you mix
baking soda and vinegar, bubbles form. Bubbles are a new substance so there was a chemical
change.
A reactant is the original substance at the beginning of chemical reaction.
A product is the substance you are left with at the end of a chemical reaction.
P5.5C How to spot a chemical change
A change in color – example bleach
A tarnish is formed – example silver turning or rust
A release of gas – example an antacid bubbling in water
A precipitate is formed – Example sour milk forms solid lumps
The release of energy – Example light and heat coming from fire
A precipitate is a solid formed from a chemical reaction of some solutions.
*Chemical changes are used to run cars and other machines. We use chemical changes to turn
our food into energy our body can use to keep us going each day.
