Unit Two: Properties of Matter
Unit Goals:
 Describe the basic properties of matter
 Introduce all subsequent topics for the school year
Warm-up Questions:
“Pick an object in the room. Describe its properties. What is it made out of? What chemical
properties do those substances have?”
“Can you change one substance to another? Give an example and explain how it works.”
“Describe an analogy for atoms as something we can see. How do they combine? What are
mixtures like?”
Assigned Readings:
http://en.wikibooks.org/wiki/General_Chemistry/Properties_of_Matter/Basic_Properties_of_Mat
ter
http://en.wikibooks.org/wiki/General_Chemistry/Properties_of_Matter/Changes_in_Matter
http://en.wikibooks.org/wiki/General_Chemistry/Properties_of_Matter/Classification_of_Matter
http://en.wikibooks.org/wiki/General_Chemistry/Numbers_Used_to_Describe_Atoms
Glencoe, pages 70 – 90, 115 – 121
Optional Readings:
http://www.newton.dep.anl.gov/askasci/phy00/phy00936.htm
http://library.thinkquest.org/18188/english/universe/theory/element.htm
Problem Set One:
Assigned Problems:
1. Classify each of the follow as a chemical or physical property
a. Iron and oxygen form rust
b. Iron is more dense than aluminum
c. Magnesium burns brightly when ignited
d. Oil and water do not mix
e. Mercury melts at 39 C
f. Silver tarnishes
g. Sodium ignites when dropped in water
2. Classify each of the following as a chemical or physical change
a. Crushing an aluminum can
b. Recycling aluminum cans to make new aluminum cans
c. Aluminum combusting with oxygen to form aluminum oxide
d. Frying an egg
e. Burning wood
3. Glencoe, Problem 6
4. “Properties are not affected by changes in temperature and pressure.” Is this statement
true or false? Explain.
5. At what temperature would 250mL of water boil (assume atmospheric pressure)?
1000mL? Is the boiling point of water an intensive or extensive property? Explain.
6. Glencoe, Mastering Problems 41 (page 94).
7. After burning a candle for three hours, it has lost half of its mass. Explain why this
example does not violate the law of conservation of mass.
Optional Problems:
1. Is the process of a banana’s ripening a physical or chemical change? Explain.
2. Sodium and chlorine combine to form sodium chloride (table salt). List the reactants and
the products of this reaction.
3. List four indicators that a chemical change has probably occurred.
Problem Set Two:
Assigned Problems:
1. Classify each of the following as heterogeneous or homogenous solutions:
a. Tap water
b. Air
c. Raisin muffin
d. Toothpaste
e. Tin-silver-copper solder
2. Describe the separation technique that could be used to separate each of the following
mixtures:
a. Two colorless liquids
b. An insoluble solid mixed with a liquid
c. Red and blue marbles of the same size and mass
d. Iron filings and sand
e. The components of ink
f. Helium and oxygen gas
3. “A mixture is the chemical bonding of two or more substances in any proportion.” Is this
statement true or false? Explain.
4. Give an example of each of the following mixture combinations. Is it homogenous or
heterogenous?:
a. Gas-gas
b. Gas-liquid
c. Gas-solid
d. Liquid-liquid
e. Liquid-solid
f. Solid-solid
5. A 78g sample of an unknown compound contains 12.4g of hydrogen. What is the percent
mass by hydrogen in the compound?
6. 1g of hydrogen reacts with 19g of fluorine. What is the percent by mass of hydrogen in
the compound formed?
7. Two unknown compounds are measured. Compound 1 contains 15g of hydrogen and
100g of oxygen. Compound 2 contains 2g of hydrogen and 32g of oxygen. Are the
compounds the same? Explain.
8. All you know about two unknown compounds is that they have the same percent by mass
of carbon. With only this information, can you be sure the compounds are the same?
Explain.
Optional Problems:
1. What is chromatography and how does it work?
Lecture Summary:
 What is matter?
o It has mass
 Measure of an object’s inertia
 Weight = Mass x Gravity
o It has volume
 Takes up space
Volume
o Density =
Mass
 Visible matter is made of atoms
o The atom is made of elementary particles:
 Protons, defines the element
 Hydrogen always has one proton
 If it has two protons, it is always helium
 Neutrons, defines the isotope
 Carbon most commonly has 12 or 14 neutrons
 Electrons, defines how the atom reacts with other atoms
o Notation Example
 126 C 2
 6 Protons
 6 Neutrons
 4 Electrons (a +2 positive charge)
o Atomic mass
 Measured in Atomic Mass Units (amu)
 Mass number is the sum of the number of protons and neutrons
 Atomic mass is averaged over samples of that element
o Moles
 Avogadro’s number: 6.02 1023
 One mole of carbon-12 = 12g
 22.4L of gas = 1 mole of gas molecules at STP (standard temperature and
pressure)
 Properties of matter
o Extensive properties depend on the amount being measured
o Intensive properties do not depend on the amount
o Physical properties can be changed without changing the identity of the substance
o Chemical properties describe how the substance reacts with other substances
 The substance’s identity is changed
 States of matter
o Most common states
 Solid
 Definite shape and volume




Liquid




Gas




Tight bonds
Can be amorphous (no particular structure)
Definite volume
Take shape of container
Weaker bonds than in a solid
Viscosity is the measure of flow thickness
No definite shape or volume
Minimal intermolecular forces
Expands to shape of container
Diffusion: the movement of molecules from an area of higher
concentration to that of a lower concentration
 Effusion: movement of particles through a hole
 If not occurring at STP, called a vapor
o By varying temperature, pressure, and energy of a substance, you can change its state
o States are physical properties
 Conservation of Mass
o Mass can never be created or destroyed
o massreactants  massproducts
 Conservation of Energy
o Energy moves and transforms in a system, but the total energy does not change
o The energy put into a system must be taken out of another system
 Elements
o A pure substance that cannot be separated out into simpler substances
o Periodic table lists the elements
 Compounds
o Two or more elements that are chemically bonded
o Can be broken into their individual elements
 Requires energy
 Chemical change
o Properties of compounds different than the properties of the individual elements
 Law of Definite Proportions
o A compound is composed of the same elements in the same proportions, regardless of
sample size
o Mass of a compound is the sum of the masses of the elements
o Percent by mass is the ratio of mass of each element to total mass of the compound
multiplied by 100
mass of element
100
 percent by mass =
mass of compound
 Law of Multiple Proportions
o Ratio between elements in a compound are whole numbers
o The compound always has the same ratio
 Mixtures
o Combination of two or more pure substances in which both substances retain their
original properties
o No chemical bonding between the substances
o Mixtures can between different phases of matter
o Homogeneous mixtures
 Called solutions
 Composition is the same throughout the mixture
 Solute dissolves in the solvent
 Gas-gas mixtures are always homogeneous
 Light passes through solutions
o Heterogeneous mixtures
 Ununiform composition
 Suspensions
 Will eventually settle and separate out
 Colloid
 Objects with different phases
 Dispersed phase in continuous medium
 Tyndall effect
o Light is caught in the colloid
o Separating mixtures
 Can be separated by mechanical means
 Filtration
 Uses a filter
 One substances passes through
 The other substance is caught in the filter
 Distillation
 Using phases to separate out substances
 Change the heat of the system to cause one substance to change phases
and separate
 Sublimation
 Similar to distillation, change the phase of a solid to a gas
 One object remains solid
 Centrifugation
 Uses the different densities to separate out substances
 Uses gravity or a centrifuge (spinning)
 Chromatography
 Separates substances based on their ability to travel along a surface
 Other means for separating mixtures:
 Combustion
 Magnetism
 Dissolving in another solution then separating
 Electrophoresis