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CHAPTER 2
PROPERTIES OF MATTER
How to classify?
Devise a classification system for the following list of things:
OrangeLime Plum ApplePear Rose Violet Daisy
Gold SilverExplain what criteria you used to place each
item.
CLASSIFYING MATTER
MATTER
PURE SUBSTANCE MIXTURE
ELEMENT COMPOUND HOMOGENEOUS HETEROGENEOUS
definitions
• Pure Substance:– MATTER THAT ALWAYS HAS THE SAME
COMPOSITION
• Mixture:– A PHYSICAL COMBINATION OF 2 OR MORE
SUBSTANCES
more definitions
Two categories of Pure Substances:Element– Can’t be broken down into simpler
substances– Organized on Periodic Table– Each contain different types of atom– Amazing: Only about 110 different atoms
makeEverything!
Elements some more
Element SYMBOLS• 1 or 2 letters (if 2, only first letter is
capitalized)• Why?– Easier – shorter for lazy scientists– Helps scientists of all nationalities communicate
AZOTE STICKSTOFFBoth have symbol N
Compound
• Can be broken down only by chemical reaction• Examples: H2O SiO2 C6H12O6
• Proportions are FIXED– All water everywhere forever has 2 H and 1 O
• Properties of Compound are DIFFERENT from the elements it’s made from
Na + Cl2 NaCl
Mixtures
• Definition: 2 or more substances physically combined
• Examples: fruit salad, salt water, steel, sand, striped cloth, maple syrup
• Keep some (most) of their individual properties.
• Classified by how well the substances are mixed.
Heterogeneous Mixture
• The parts are noticeably different from one another.
• fruit salad, sand, striped cloth
Homogeneous Mixture
• The parts are so evenly mixed the individual parts are difficult or impossible to distinguish.
• Sea water, steel, maple syrup
Special Types of Mixtures
1. SOLUTIONFormed when one substance DISSOLVES in
anotherKool-Aid, Antifreeze, Oxygen in waterDissolved particles are so small:– Do not separate over time– If filtered, no particles are trapped– Light will pass through without being scattered
2. SUSPENSIONA heterogeneous mixture that will separate
over time.Muddy water, OJ with pulp, Apple ciderDissolved particles are larger:– Will separate over time– If filtered, particles will be trapped– Light passing into it is scattered in all directions
3. COLLOIDA mixture with larger particles than solution
but smaller than suspensionFog, milk, styrofoam, blood, gelatinMedium-sized particles – Will not separate into layers – A filter traps no particles– Will scatter light in all directions
CHECK YOURSELF
Place the following in order from smallest to largest particle size
SUSPENSION, SOLUTION, COLLOID
SOLUTION
COLLOID
SUSPENSION
SMALLEST
LARGEST
• Fill in the diagram
MATTER
MIXTUREPURE SUBSTANCE
ELEMENT COMPOUND
HOMOGENEOUS HETEROGENEOUS
SOLUTION COLLOID SUSPENSION
Physical PropertiesAny characteristic that can be measured or
observed without changing the composition of the material.
• VISCOSITY– Ability to flow…slow flowing (syrup) = viscous
• CONDUCTIVITY– Ability to conduct heat and/or electricity
• MALLEABILITY– Ability to bend or be hammered without breaking
• HARDNESS– Measures resistance to shape change
• Melting Point– Temp at which particles become free to pass each
other• Boiling Point– Temp at which particles gain total freedom from
one another• Density– Amount of matter per unit volume
V
mD
Uses of Physical Properties
1. Identify a substance: List of properties is like a fingerprint
2. Choosing a substance:– Bulletproof vest?
– Artificial Heart?
3. Mixture Separation– Filtration
Uses differences in particle size– Distillation
Uses differences in boiling point
Divide this list into two groups:
• Burning a marshmallow• Cutting paper• Melting an ice cube• Smashing a light bulb
• Rusting car• Dissolving salt in water• Baking soda + Vinegar
• Dissolving salt in water• Cutting paper• Melting an ice cube• Smashing a light bulb
• Burning a marshmallow• Rusting car• Baking soda + Vinegar
• Dissolving salt in water• Cutting paper• Melting an ice cube• Smashing a light bulb
This list: All change the shape/form but the substance remains the same
PHYSICAL CHANGES
Chemical Properties
Can be observed only when the substance is changing into a different substance
• Burning a marshmallow• Rusting car• Baking soda + Vinegar
Two Names:1. Flammability – Ability to burn in the
presence of oxygen2. Reactivity – describes how readily a
substance combines chemically with another
Sodium is reactive with waterIron is not reactive with water
Magnesium is reactive with acid
Recognizing Chemical Change
• Color Change– Copper turns green with age– Rust
• Form a Gas– Baking soda + Vinegar– Magnesium + Acid
• Form a Precipitate– lead nitrate + sodium iodide
Practice with P/C Changes
Shattering Glass P CSunburn P CBleaching clothes P CBaking cookies P CFolding laundry P CRipping your pants P CHydrogen peroxide on a cut P C