September 18th, 2015
In 1927, Columbia Phonograph Broadcasting System went
on the air with 47 radio stations. However, the radio
network lost money in its first year, and on 18 Jan 1929
Columbia Records sold out to a group of private investors
for $400,000, headed by William S. Paley, a Philadelphia
cigar manufacturer. The radio network was renamed The
Columbia Broadcasting System (CBS).
SciFir
 Discuss Book
 Discuss chemical and physical
properties

SciFri September 18th, 2015 Bamboo Cycle Rolls Out
Changes in Properties
Goals: describe coming physical and
chemical changes
 Determine between chemical and
physical properties
 Identify intensive and extensive
characteristics
 Suggested Reading: section 3.2
changes in properties pages 56 -62

A reaction where a new substance is formed.
Chemical bonds are broken and reformed.
Difficult to reverse the reaction.
Formation of a gas
Color change (that is not a result from dilution
or color mixing
Emission or absorption of heat (temperature chan
Formation of a Precipitate
Emission of light
Iron rusting
Leaves changing colors
Fruit ripening
Wood burning
Reactions that absorb energy
Get “endo” the house,
because it’s COLD!
Endothermic processes
melting ice cubes
conversion of frost to water vapor
evaporation of water
forming a cation from an atom in the gas phase
baking bread
cooking an egg
producing sugar by photosynthesis
separating ion pairs
melting solid salts
Reactions that give off Heat
Explosion !
Exothermic processes
making ice cubes
formation of snow in clouds
condensation of rain from water vapor
a candle flame
mixing sodium sulfite and bleach
rusting iron
burning sugar
mixing water with calcium chloride
State change
Form change – ripping, tearing, bending, size
change
Dissolving
Magnetization
No new substance is formed.
No chemical bonds are broken and reformed.
Easy to reverse the reaction.
The form or state of a material may change
but not its basic composition or properties.
What is a property?

Property: a
characteristic of a
substance that can
be observed
Physical Property
Physical property: a property that can be
observed without changing the identity of the
substance.
Examples:
• luster
• melting point
• malleability: the ability
to be hammered into a
thin sheet
• boiling point
• ductility: the ability to
be stretched into a wire
• solubility
• density
• specific heat
Special Physical Properties

Melting point: the temperature at
which a substance changes from a
solid to a liquid at a given pressure
water = 0oC

Boiling point: the temperature at
which a substance changes from a
liquid to a gas at a given pressure
water = 100oC
Chemical Properties

Chemical property: a property that
can only be observed by changing the
identity of the substance
Examples:
•flammability
•ability to rust
•reactivity with vinegar
Intensive/Extensive Properties
Assignment
None
 Unit exam Wednesday, September 23rd
