2. Chemical & Physical Change
Physical Changes: Any change that
alters the form, shape, or appearance
of a substance but does not change it
into a new substance.
EXAMPLE: If I were to toss fresh berries
into a blender and make a fruit smoothie-
it would still be fruit, just mashed into
smaller pieces.
3. Chemical & Physical Change
Chemical Changes: a change that a
substance undergoes where a totally
new substance is the result.
EXAMPLE: In the magnesium lab, we
burned magnesium and after it’s chemical
change the result was magnesium oxide.
It was no longer metal!!
4. Did a chemical reaction occur??
Was light given off? It was chemical.
Was gas released? It was chemical.
Was heat given off? It was chemical.
Was energy released? It was
chemical.
5. Chem vs. Phys Propeties
Chemical Properties- The
characteristic of a substance that
describes its ability to change into a
new substance
Example: Burning of Magnesium into
MgO
Physical Properties- A characteristic of
a substance that can be observed
without changing the substance into a
new substance
Example: Ice Melting, Cutting a piece of
paper
6. Bonding & Chemical Reactions
In order for a chemical reaction to
have taken place, bonds must have
been broken and re-created!! Atoms
rearrange to create something totally
new.
Bonds can change from one form to
another; covalently bonded atoms can
rearrange to create ionic bonded atoms
(like with the Mg lab)
7. Reactions
Remember, when atoms come
together to form compounds, the new
compounds produced have different
properties than the atoms did before.
No exploding salt!!!!
8. Balancing equations
Due to the conservation of matter,
equations MUST be balanced!
Atoms cannot be created or destroyed!
Thus, the atoms in the products must
equal the total atoms in the reactants
REMEMBER: The atoms are only being
rearranged!
9. Let’s try one…
N2 + O2 ---> N2O5
2 N 2 N
2 O 5 O
We need to balance out the Oxygen first, then the
Nitrogen. This gives us…
2N2 + 5O2 ---> 2N2O5
4 N 4 N
10 O 10 O
10. Let’s do another, for fun!!
Fe + HCl ---> FeCl2 +H2
1 Fe 1 Fe
1 H 2 H
1 Cl 2 Cl
Fe + 2HCl ---> FeCl2 +H2
11. One More…
C2H4 + O2 ---> CO2 + H2O
2 C 1 C
4 H 2 H
2 O 3 O
C2H4 + 3O2 ---> 2CO2 + 2H2O
13. Acids and Bases
An Acid is a chemical compound, that,
when dissolved in water has a pH of
less than 7.
Acids taste sour, react with metals and
carbonates and will turn blue litmus
paper red.
Acids are corrosive- they eat away at
other materials.
14. Acids and Bases
Bases are chemical compounds that,
when dissolved in water, have a pH of
above 7.
Bases taste bitter, feel slippery and
turn red litmus paper blue.
Bases are corrosive- they eat away
materials.
15. Uses for Acids:
Acids are naturally in many of the foods
we eat :Tomatoes, lemons, oranges,
and even leafy green veggies!
Acids are also used in many fertilizers.
Acids can also be found in batteries
16. Uses for Bases
Cement is made using bases
Many cleaning solutions used in the
home are bases (drain cleaner, glass
cleaner, bleach, soap)
Bases can also be found in baked
goods such as breads, cakes, and
cookies!
17. The pH scale!!!!
The pH scale is a range of values from
0-14 that express the concentration of
hydrogen ions in a solution.
The more hydrogen ions, the lower the
number on the pH scale.
18. Acids & Bases: pH scale
Acids range from 0-6
Acids have the most amount of
hydrogen ions.
Bases range from 8-14
Bases have the least amount of
hydrogen ions.
7 on the scale is neutral (neither)
19.
20. Neutralizing Acids & Bases
The reaction between acids and bases
is a called neutralization.
The neutralization of acids and bases
depends on the identities, volumes
and concentrations of the reactants.
Salts will typically form as a result of
acids and bases neutralizing.
22. Carbon! It’s special!
Because of it’s very special ability to
combine in any ways with itself and
other elements it has a central roll in
the chemistry of living organisms!
23. CHONPS!
Living organisms are made of
molecules consisting largely of:
Carbon
Hydrogen
Oxygen
Nitrogen
Phosphorus
Sulfur
