chapter 3. matter – anything that has mass and takes up space everything around us mass:...
TRANSCRIPT
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 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
D = MV
1 cm3 = 1 mL1 dm3 = 1 L
Density (kg/m3 or g/cm3 or g/mL)mass per volume
Chemical Property describes the ability of a substance to be
observed reacting with or changing into another substance
Examples: melting point
flammable
density
magnetic
tarnishes in air
physical
chemical
physical
physical
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 =
Condensation =
Melting =
Freezing =
Sublimation =
Liquid -> Gas
Gas -> Liquid
Solid -> Liquid
Liquid -> Solid
Solid -> Gas
Temp, oC
Solid only, Q = m ΔT Cpsolid
Q = mol x ΔHfusion
Solid & liquidLiquid onlyQ= m ΔT Cpliquid
Q = mol x ΔHvapor
Liquid & gas
Time, min
Temperature vs. Time
Gas Only
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
dissolving in water
burning a log
melting ice
grinding spices
chemical
physical
chemical
physical
physical
Exothermic- heat energy EXITS the system
surroundings usually feel warmer1 g H2O (g) 1 g H2O (l) + 2260 Jex. 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
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
Can it be physically separated?
Homogeneous Mixture
(solution)
Heterogeneous Mixture Compound Element
MIXTURE PURE SUBSTANCE
yes no
Can it be chemically decomposed?
noyesIs the composition uniform?
noyes
Examples: graphite
pepper
sugar (sucrose)
paint
soda
element
hetero. mixture
compound
hetero. mixture
solution
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)
Variable combination of 2 or more pure substances, each retains its chemical identity & properties.
Heterogeneous Homogeneous
Homogeneous: are uniform throughout Solutions very small particles particles don’t settle EX: rubbing alcohol, gasoline, soda
Heterogeneous medium-sized to
large-sized particles
particles may or may not settle
EX: milk, fresh-squeezed
lemonade
Examples: tea
muddy water
fog
saltwater
Italian salad dressing
Answers: Solution
Heterogeneous
Heterogeneous
Solution
Heterogeneous
1. Metals: usually solid, good conductors of heat/electricity, malleable, and ductile
2. Nonmetals: solid, liquid or gas, brittle, poor conductors
3. Metalloids: transition between metals and nonmetals, semiconductors
Atom: Composed of protons, electrons, and
neutrons Smallest particle of matter that can be
identified as one elementMolecules:
A collection of atoms chemically bonded together
May be element or compound
Electron: Negative charge Used in bonding (very mobile)
Proton: Positive charge Located in nucleus Determine identity of atom
Neutron Neutral (no charge) Helps determine mass of the atom Located in nucleus
+
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 Visually Magnetism Filtration Distillation Crystallization Chromatography
+Filtration
Used to separate heterogeneous mixtures composed of solids and liquids
Uses a porous barrier to separate the solid from the liquid
Liquid passes through leaving the solid in the filter paper
+Distillation
Used to separate homogeneous mixtures
Based on differences in boiling points of substances involved
+Crystallization
Separation technique that results in the formation of pure solid particles from a solution containing the dissolved substance
As one substance evaporates, the dissolved substance comes out of solution and collects as crystals
Produces highly pure solids
Rocky candy is an example of this
+Chromatography
Separates components of a mixture based on ability of each component to be drawn across the surface of another material
Mixture is usually liquid and is usually drawn across chromatography paper
Separation occurs because various components travel at different rates
Components with strongest attraction for paper travel the slowest