1. Matter and Change
Chemistry
Chapter 1

2. Try to Answer the Following Questions
1. A compound is formed by…
A single element
Two or more atoms
Two or more nuclei
Electrons and neutrons
Which statement best describes atoms and molecules in a liquid?
They vibrate rapidly
They form a definite structure
They slide past each other
They cannot be rearranged
What is the process of a liquid changing to a gas called?
Ice melting into water is a physical or chemical change?
Which state of matter has neither a definite shape nor definite volume?

3. How did you do? “B”: two or more atoms
“C”: atoms and molecules in a liquid slide past each other
Evaporation
Physical
Gas

4. Introduction What is chemistry?
The study of the composition of substances and the changes (both physical and chemical) they undergo
What lead to the development of chemistry?
Alchemy
What other sciences does chemistry contribute to?
Biology
Geology
Physics

5. What does a Chemist do? Develop new products (meds., cosmetics)
Find methods to reduce pollution/clean up environment
Teaching
Analyzing substances
Quality of manufactured products
Applied Chemistry: using knowledge to attain specific goals (a.k.a. chemical technology)
Knowledge can be used to help or hurt people/environment

6. Branches Organic Chemistry Inorganic Chemistry Analytical Chemistry
The study of all substances that come from carbon
Inorganic Chemistry
The study of all substances without carbon
Analytical Chemistry
The study of the composition of substances
Physical Chemistry
Theories and experiments that describe the behavior of chemistry
Biochemistry
The study of chemistry of living organisms

7. Hypothesis vs. Theory vs. Scientific Law
A HYPOTHESIS is a proposed reason for what is observed and it needs to be tested by means of an experiment
A THEORY is a thoroughly tested explanation of why experiments give certain results.
A theory tends to explain WHY things happen. You cannot prove a theory.
Scientific Law is a concise statement that summarizes the results of a broad spectrum of observations and experiments.
Scientific Law tends to explain WHAT things happen. You can prove a scientific law.

8. Why does it “matter”? What is matter? What is mass?
“Everything that takes up space and has mass”
“Stuff”
What is mass?
Amount of matter an object contains
“How much stuff an object has”
**This is NOT the same as weight

9. Substances vs Mixtures
Matter is broken into categories. Matter can be either a substance or a mixture.
A substance is a particular kind of matter that has a uniform composition. This means that no matter the sample it will always have the same physical properties.
Eg. Elements and compounds
Other examples are: salt (NaCl), Fe, Ag, Pb, water
What about lemonade?

10. Mixtures
A mixture is a physical blend of two or more substances. It has a variable composition and can be made of different ratios of substances.
Mixtures are ALWAYS physical changes

11. Types of mixtures Heterogeneous mixtures -not uniform in composition
-more than one phase (a phase is a part of a system that is uniform in composition and physical state)
-examples: tossed salad, gravel mix, rock, river water

12. Homogeneous mixtures
-uniform in composition
-also called a solution
-easily confused with substances
-examples: salt water

13. A good question to ask yourself when trying to decide if something is a substance or a homogeneous mixture is to ask yourself if there is more than one kind of this material.
What is gasoline?
What is milk?
Are there different concentrations of salt?

14. Separating a Mixture
There are several ways to separate a mixture. A good way to figure out if matter is a substance or a solution is to see if you can separate it into parts by doing one of the following:
Physical separation
Filter (particle size, uses gravity)
Magnet (magnetism)
Decanting-pouring off a liquid (density)
Distillation (boiling point)
Centrifuging (density)
Chromatography (separates based on solubility)
Crystallization

15. Lab: Classifying Matter
At each station, record answers to the following:
1) Identify the category of matter: a. Is it a pure substance? If so then is it an element or is it a compound?
b. Is it a mixture? If so, then is it a heterogeneous mixture or homogeneous mixture?
c. Write down the criteria you use for your categorization schemes.
2) Devise a separation strategy for any mixtures found. In other words, if you think you’ve spotted a mixture, how would you separate it into different components, and (if possible) all the way to the pure substances that comprise the mixture? (Remember, pure substances cannot be separated by physical means. They must be separated chemically, or, in the case of elements, by splitting atoms! That’s beyond the scope of the activity for the day.)   

16. Physical Properties
Matter contains both physical and chemical properties.
A physical property is a quality or condition of a substance that can be measured or observed without changing the substance’s composition.
Examples: Color, mass, density, hardness, odor, boiling point, solubility

17. Chemical Properties
Chemical properties are a little more difficult to determine. A chemical property is the ability of a substance to undergo chemical reactions
IE:
Rot, rust, decompose, decay, grow ferment
You know that a chemical change has taken place because of a substance’s chemical properties.

18. Chemical vs. Physical Changes
Chemical Change
A change in the composition of a substance OR
Changing a substance to form a new substance
Examples: fermenting, rotting, burning, color change, gas given off
Physical Change
A change in a substance without a change in its composition
Examples: mixing, cutting, changing from a solid to a liquid

19. Physical Property
Something that can be observed without altering the chemical state
Example: color, boiling point

20. Physical Change A change that occurs without forming a new substance
Example: melting
DOES NOT FORM OR BREAK BONDS!

21. Chemical Property
Property of a substance related to a chemical change undergone by the substance
Example: metal dulls in air

22. Chemical Change
A reaction occurs and one or more new substances are formed
Example: Rusty cars

23. Figure it out- Chemical or Physical?
Metals are shiny
Argon is put in light bulbs because it doesn’t react
Milk gets sour when left out
Metals can be made into wires
Bread rises when cooked
Nonmetals are not able to conduct electricity

24. What is the basic difference between a chemical and a physical change?
After a physical change, it is still the same substance (composition).
-After a chemical change, you have a NEW substance

25. States of Matter There are four states of matter: solid, liquid, gas
Solid -definite shape, definite volume
Liquid -indefinite shape, definite volume
Gas -indefinite shape, indefinite volume
Plasma –gas like
What is compressibility?
Ability to squash something into a smaller volume

26. Solid, Liquid, Gas
(a) Particles in solid (b) Particles in liquid (c) Particles in gas

27. Gas, Liquid, and Solid Gas Liquid Solid
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 441

28. Some Properties of Solids, Liquids, and Gases
Property Solid Liquid Gas
Shape Has definite shape Takes the shape of Takes the shape
the container of its container
Volume Has a definite volume Has a definite volume Fills the volume of
the container
Arrangement of Fixed, very close Random, close Random, far apart
Particles
Interactions between Very strong Strong Essentially none
particles

29. Solid
H2O(s) Ice
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 31

30. Ice H2O(s) Ice Photograph of ice model Photograph of snowflakes
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 31

31. Liquid In a liquid H2O(l) Water molecules are in constant motion
there are appreciable
intermolecular forces
molecules are close
together
Liquids are almost
incompressible
Liquids do not fill the
container
some writing from Kotz (PowerPoints online)
H2O(l) Water
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 31

32. Liquids The two key properties we need to describe are
EVAPORATION and its opposite CONDENSATION
add energy and break intermolecular bonds
EVAPORATION
CONDENSATION
release energy and form intermolecular bonds

33. Gas
H2O(g) Steam
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 31

34. States of Matter
Solid, Liquid, Gas are the three states of matter we will deal with.
Plasma and Neutron star are also states of matter.
For more information about plasma and neutron stars try the following links:
Coalition for Plasma Science – What is plasma?
Neutron Stars and Pulsars – Introduction

35. Evaporation
To evaporate, molecules must have sufficient energy to break IM forces.
Molecules at the surface break away and become gas.
Only those with enough KE escape.
Breaking IM forces requires energy. The process of evaporation is endothermic.
Evaporation is a cooling process.
It requires heat.

36. Condensation Change from gas to liquid
Achieves a dynamic equilibrium with vaporization in a closed system.
What is a closed system?
A closed system means matter
can’t go in or out. (put a cork in it)
What the heck is a “dynamic equilibrium?”

37. Dynamic Equilibrium
When first sealed, the molecules gradually escape the surface of the liquid.
As the molecules build up above the liquid - some condense back to a liquid.
The rate at which the molecules evaporate and condense are equal.

38. Rate of Vaporization = Rate of Condensation
Dynamic Equilibrium
As time goes by the rate of vaporization remains constant but the rate of condensation increases because there are more molecules to condense.
Equilibrium is reached when:
Rate of Vaporization = Rate of Condensation
Molecules are constantly changing phase “dynamic”
`The total amount of liquid and vapor remains constant “equilibrium”

39. Vaporization
Vaporization is an endothermic process - it requires heat.
Energy is required to overcome intermolecular forces
Responsible for cool earth
Why we sweat

40. Energy Changes Accompanying Phase Changes
Gas
Vaporization
Condensation
Sublimation
Deposition
Energy of system
Liquid
Melting
Freezing
Solid
Brown, LeMay, Bursten, Chemistry 2000, page 405