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