Focus Question: What are (chemical changes)? or (chemical reactions)
 When substances are mixed together and form a new substance which cannot be easily
separated. The new substance has different properties than the original substances.
 Chemical reactions can occur when the new substance (with new properties):
1. Heats up.
2. Lights up.
3. Forms a precipitate.
4. A gas is released. (It fizzes or bubbles.)
5. It changes colors.
 Precipitate: When a substance deposits in the bottom of the cup in solid form.
 Examples of chemical changes (or chemical reactions):
1. Burning
2. Rusting
3. Baking a cake
4. Combining vinegar and baking soda. (Carbon dioxide is released and a new
substance with new is left on the bottom of the cup.
 To verify a chemical reaction occurs: Check to see if new properties are formed.
 Reacting: When 2 substances are mixed together and a new substance is created.
(chemical reaction)
 Dissolving: Occurs when substances keep their own properties. You can no longer see
the substances. (Physical changes
Solutions)
Differences Between Physical and Chemical Changes
Physical Changes (Mixtures and
Solutions)
When the substances are mixed
together, they keep their original
properties.
Chemical Changes or Chemical
Reactions
When the substance are mixed
together, they do NOT keep their
properties.
NO new substances are formed.
The substances combine and make a
new substance.
The substances are easily separated.
The substance are almost impossible to
separate.