Post on 02-Jan-2016
transcript
Matter, Classify Changes of Matter
At the conclusion of our time together, you should be able to:
1. Characterize various changes of matter2. Recognize that a change of state in
matter is a physical change
PhysicalPhysical
Physical ChangePhysical Change
A change in matter from one form to another without changing its chemical properties
(most can be reversed)No change in atoms/molecules
Physical Change
Examples = Change in state or phase change Dissolving Compressing Light emission/absorption Electrons passing through metals
Physical Change
More Examples =
boiling of a liquid melting of a solid dissolving a solid in a
liquid to give a homogeneous mixture
making a solution
ChemicalChemical
Chemical ChangeChemical Change
Bonds are made / broken Change in oxidation states Bonds are made / broken Change in oxidation states
Cl-1 Cl-1
21
Li +1
Examples of Chemical Change
Chemical change or chemical reaction — transformation of one or more atoms or molecules into one or more different molecules.
• Burning hydrogen (H2) in oxygen (O2) gives H2O.
Sure Signs of a Chemical Change“Chemists Get Practice Trying Labs”
Color Change Gas Produced (not from
boiling!) Precipitate – a solid
formed by mixing two liquids together
Temperature Change Light
Remember the Law of Conservation of Mass
In a physical change or a chemical reaction, mass is neither created or destroyed
(Antoine Lavoisier)
Matter, Classify Changes of Matter
Let’s see if you can:
1. Characterize various changes of matter2. Recognize that a change of state in
matter is a physical change
Physical vs. Chemical Change
Examples:
melting
flame produced
paper cut
dissolving salt
in water
tarnishes in air
physical
chemical
physical
physical
chemical
Examples:
rusting iron
mixing mud and
water
burning a log
freezing water
grinding spices
Physical vs. Chemical Change
chemical
physical
chemical
physical
physical
A difference between physical change and chemical change is that
1. chemical change involves energy while physical change does not.
2. physical change involves energy while chemical change does not.
3. different kinds of molecules are present after a physical change but not after a chemical change.
4. different kinds of molecules are present after a chemical change but not after a physical change
In making a pizza, which process involves a chemical change?
1. Mixing spices for the sauce
2. Slicing pepperoni for the topping
3. Spreading cheese on the pizza
4. Baking the dough to form the crust
In making a pizza, which process involves a chemical change?
1. Mixing spices for the sauce
2. Slicing pepperoni for the topping
3. Spreading cheese on the pizza
4. Baking the dough to form the crust
All You Really Need To Know You Can Learn From Noah's Ark
11. Remember that the ark was built by amateurs; the Titanic was built by professionals.
12. Remember that woodpeckers inside are a larger threat than the storm outside.
Matter, Properties of Matter
At the conclusion of our time together, you should be able to:
1. Explain the difference between the extensive and intensive properties and other types of properties
2. Distinguish between a physical property and chemical property
The Nature of MatterThe Nature of Matter
Chemists are interested in the nature of matter and how this is related to its
atoms and molecules.
Gold Mercury
Chemistry & Matter
We can explore the MACROSCOPIC world — what we can see —
to understand the PARTICULATE worlds we cannot see.
We write SYMBOLS to describe these worlds.
A Chemist’s View
2 H2(g) + O2 (g) --> 2 H2O(g)
MacroscopicMacroscopic
SymbolicSymbolic
ParticulateParticulate
Properties of Matter
2 Types:
Extensive – depend on the amount of the sample
Always involves a number with unit Examples = volume
masslength
Properties of Matter (cont.)
Intensive – does not depend on the amount of the sample
Usually does not involve a number Examples = density
melting, boiling point
malleabilityductilitycolorodor
Properties
Every substance has a unique set of properties (characteristics that identify that substance)
Physical Properties- Properties that can be measured
without changing the identity and composition of the substance
Graphite — this layer structure of carbon atoms reflects its physical properties.
List Some Physical Properties of:
Chemical Properties
Properties that describe the way a substance may change to form other substances
Only observed when a chemical reaction takes place
Chemical Property Examples
Combustible Reactive with water or acid Flammable Corrosive Decomposes in air
Physical vs. Chemical Properties
Physical Properties- Properties that can be measured
without changing the identity and composition of the substance
Chemical Properties- Properties that can be measured by
changing the identity and composition of the substance
Matter, Properties of Matter
Let’s see if you can:
1. Explain the difference between the extensive and intensive properties and other types of properties
2. Distinguish between a physical property and chemical property
Properties of Matter
2 Types:
Extensive – depends on the amount of the sample Intensive – does not depend on the amount of the
sample
Physical vs. Chemical Properties
Physical Properties- Properties that can be measured
without changing the identity and composition of the substance
Chemical Properties- Properties that can be measured by
changing the identity and composition of the substance
Physical vs. Chemical Property
Examples:
melts at 55oF
flammable
will tear easily
will dissolve in
water
will tarnish
physical
chemical
physical
physical
chemical
Examples:
will rust
mixture can be
separated by boiling
burns
freezes at -20oC
can be crushed
Physical vs. Chemical Properties
chemical
physical
chemical
physical
physical
Familiar Saying
A rotating lithoidal fragment never accrues lichen.
A rolling stone gathers no moss!!
Oobleck Time!!