Science Test Review
Pure Substances and Mixtures
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Particle Theory: Matter is made up of tiny particles with space between them
Scientists classify matter into 5 different phases:
o Solid: Particles are close together. They can only move from side to side.
o Liquid: Particles are slightly farther apart. Slides pass each other easily.
o Gas: Particles are far apart and can move in all directions.
o Colloid: Particle mix completely together, however they remain separate.
Ex. Jello, Shaving Gel, Smoke
o Suspensions: Particles mix together, however remain separate and the
heavier particles settle. Ex. Muddy water, four and water.
There are many different types of particles. The differences in the particles are what
give the substances different properties. (Remember the soap and the tar particles
on the magic school bus!)
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Pure Substance: A pure substance only containing one type of particle.
Mixture: A substance that is a mixture of two or more pure substances. Mixtures
can be any combination of solids, liquids, and gases. For example- Pop- Includes
a liquid (Water), Solid (sugar), and gas (Carbon dioxide).
Heterogeneous Mixture: Also known as a mechanical mixture- Made up of two
or more types of particles that can clearly be seen, For example: Sand and water.
Homogeneous Mixture: Also known as a solution- Made up of two or more pure
substances that mix completely together and look like one substance.
Solute- That which dissolves. Ie. Sugar
Solvent- That which the solute dissolves in. Ie. Water
Solubility- The solubility of a solute is the exact amount of solute required to
form a saturated solution in a particular solvent at a certain temperature. Ex.
Sugar is soluble in water; it takes 179g of sugar in 100mL of water to create a
saturated solution at 0 degrees Celsius. Oil is insoluble (does not dissolve) in
water.
Saturated Solution- The solute particles fill all of the available spaces between
the solvent particles.
Dilute Solution- the solute particles fill only some of the spaces between the
solvent particles.
Concentrated Solution- The solute particles fill most of the available spaces
between solvent particles.
Supersaturated- A solution that contains more of the solute than would be found
in a saturated solutions- more solute particles then available spaces between
solvent particles.
Unsaturated Solutions- Occur any time there are spaces left between the solvent
particles. Both concentrated and dilute solutions are
Alloy- Is a metal made of two or more solids. Ex. Brass is an alloy of silver and
copper, Tin is an alloy of iron and zinc, Lead is an alloy of brass and tin.
Dissolving: Particles of one substance mix completely with particles of the other.
How do solutions form?
-A solution occurs when all the solute particles break apart from their
original form and mix completely with the particles of the other substance(s). When
creating a solution smaller particles tend to dissolve faster than large ones.
There are two things that you should know affect the rate of dissolving:
1. Temperature
2. Size of the particles
 Not all solutions are liquids!!
 Air is a solution
 Steel is a solution
 2 main solution traits:
 Particles are too small to see
 Particles are evenly spread out.
 Two parts of a solution:
 Solvent- Does the dissolving
 Solute- Is dissolved
Mixtures
 3 Properties of mixtures:
 Each substance retains all its own chemical properties.
 The substances can be present in any amount.
 The substances in a mixture can be separated by simple physical
means.
 2 Types of Mixtures:
 Heterogeneous- not mixed well, can see both substances.
 Homogeneous- Well mixed, looks like one substance.