Transcript Matter and Energy Notes

Chapter 3

Matter – anything that has mass and takes up space
 Everything around us
 Mass: measurement that reflects the amount of matter
(usually in grams)
 Volume: the amount of space something takes up

Chemistry – the study of matter and the changes it
undergoes

Solids
 particles vibrate but can’t move around
 fixed shape
 fixed volume
 incompressible

Liquids
 particles can move around but
are still close together
 variable shape
 fixed volume
 Virtually incompressible

Gases
 particles can separate and move
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


throughout container
variable shape
variable volume
Easily compressed
Vapor = gaseous state of a substance
that is a liquid or solid at room
temperature

Plasma
 atoms collide with enough energy to break into
charged particles (+/-)
 gas-like, variable
shape & volume
 stars, fluorescent
light bulbs, TV tubes
II. Properties & Changes in Matter (p.73-79)
Extensive vs. Intensive
Physical vs. Chemical

Physical Property
 can be observed & measured without changing
the identity of the substance

Physical properties can be described as one of
2 types:

Extensive Property
 depends on the amount of matter present
(example: length, mass, volume)

Intensive Property
 depends on the identity of substance, not the
amount (example: scent, density, melting point)
Derived units = Combination of
base units
 Volume (m3 or cm3 or mL)

 length  length  length
 Or measured using a graduated
cylinder
 Density (kg/m3 or g/cm3 or
g/mL)
mass per volume
1 cm3 = 1 mL
1 dm3 = 1 L
M
D=
V

Chemical Property
 describes the ability of a substance to be observed
reacting with or changing into another substance

Examples:
 melting point
physical
 flammable
chemical
 density
physical
 magnetic
physical
 tarnishes in air
chemical

Physical Change
 changes the form of a substance without
changing its identity
 properties remain the same

Examples: cutting a sheet of paper, breaking
a crystal, all phase changes
Evaporation =
Liquid -> Gas
Condensation =
Gas -> Liquid
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Melting =
Solid -> Liquid
Freezing =
Liquid -> Solid
Sublimation =
Solid -> Gas
Temperature vs. Time
Q = mol x ΔHvapor
Liquid & gas
Gas Only
Temp,
oC
Q = mol x ΔHfusion
Solid & liquid
Solid only, Q = m ΔT Cpsolid
Time, min
Liquid only
Q= m ΔT Cpliquid

Process that involves one or more substances
changing into a new substance
 Commonly referred to as a chemical reaction
 New substances have different compositions and
properties from original substances
 Reaction involves reactants reacting to
produce products

Signs of a Chemical Change
 change in color or odor
 formation of a gas (bubbles)
 formation of a precipitate (solid)
 change in light or heat

Examples:
 rusting iron
chemical
 dissolving in water
physical
 burning a log
chemical
 melting ice
physical
 grinding spices
physical
Exothermic- heat energy EXITS the system
 surroundings usually feel warmer
 1 g H2O (g)  1 g H2O (l) + 2260 J
 ex. Combustion, evaporation of water
Endothermic- heat energy ENTERS the system
- heat absorbed from surroundings
- surroundings usually feel cooler
- 1 g H2O (s) + 333 J  1 g H2O (l)
- 1 g H2O (l) + 2260 J  1 g H2O (g)
- ex. Cold packs, melting ice
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Although chemical changes occur, mass is
neither created nor destroyed in a chemical
reaction
Mass of reactants equals mass of products
massreactants = massproducts
A+BC
III. Classification of Matter (pp. 80-87)
Matter Flowchart
Pure Substances
Mixtures
MATTER
yes
Can it be physically
separated?
MIXTURE
yes
Is the composition
uniform?
Homogeneous
Mixture
(solution)
no
PURE SUBSTANCE
no
Heterogeneous
Mixture
yes
Can it be chemically
decomposed?
Compound
no
Element
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Examples:
 graphite
element
 pepper
hetero. mixture
 sugar (sucrose)
compound
 paint
hetero. mixture
 soda
solution
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Element
 composed of one type of identical atoms
 EX: copper wire, aluminum foil

Compound
 composed of 2 or more elements in a
fixed ratio (bonded together)
 properties differ from those of
individual elements
 EX: table salt (NaCl)
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Variable combination of 2 or more pure
substances, each retains its chemical identity &
properties.
Heterogeneous
Homogeneous
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Homogeneous: are uniform throughout
 Solutions
 very small particles
 particles don’t settle
 EX: rubbing alcohol, gasoline, soda
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Heterogeneous
 medium-sized to
large-sized particles
 particles may or may
not settle
 EX: milk, freshsqueezed
lemonade
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Examples:
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Answers:
 tea
 Solution
 muddy water
 Heterogeneous
 fog
 Heterogeneous
 saltwater
 Solution
 Italian salad dressing
 Heterogeneous
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1. Metals: usually solid, good conductors of
heat/electricity, malleable, and ductile
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2. Nonmetals: solid, liquid or gas, brittle,
poor conductors

3. Metalloids: transition between metals and
nonmetals, semiconductors
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Atom:
 Composed of protons, electrons, and neutrons
 Smallest particle of matter that can be identified
as one element
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Molecules:
 A collection of atoms chemically bonded together
 May be element or compound
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Electron:
 Negative charge
 Used in bonding (very mobile)
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Proton:
 Positive charge
 Located in nucleus
 Determine identity of atom
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Neutron
 Neutral (no charge)
 Helps determine mass of the atom
 Located in nucleus
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Separation Methods
Ways to separate mixtures – Chapter 3: Matter
& Its Properties
+
Separating Mixtures

Substances in a mixture are physically combined, so
processes bases on differences in physical properties are
used to separate component

Numerous techniques have been developed to separate
mixtures to study components
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Visually

Magnetism

Filtration
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Distillation
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Crystallization

Chromatography
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Filtration
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Used to separate heterogeneous mixtures
composed of solids and liquids
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Uses a porous barrier to separate the solid
from the liquid
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Liquid passes through leaving the solid in the
filter paper
+
Distillation
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Used to separate
homogeneous mixtures
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Based on differences in
boiling points of substances
involved
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Crystallization
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Separation technique that results in
the formation of pure solid
particles from a solution containing
the dissolved substance
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As one substance evaporates, the
dissolved substance comes out of
solution and collects as crystals
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Produces highly pure solids
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Rocky candy is an example of this
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Chromatography
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Separates components of a mixture based
on ability of each component to be drawn
across the surface of another material
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Mixture is usually liquid and is usually
drawn across chromatography paper
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Separation occurs because various
components travel at different rates
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Components with strongest attraction for
paper travel the slowest