Test is on
Unit 2A Study Guide
States of Matter
Elements, Compounds and Mixtures
Wednesday, October
2 nd !
Answer all questions on a separate page in your science notebook!
1.
How can we describe the 4 states of matter in terms of energy and particle motion? State and volume? a.
Solid: definite shape and volume. Particles vibrate in place and have the least amount of energy. b.
Liquids: takes the shape of the container but has a definite volume.
Particles have more energy than in the solid state so they can slide past each other. c.
Gas: Indefinite shape and volume, fills any available space.
Particles have even more energy then when in liquid form, the attraction between particles is minimal and particles are moving quickly. d.
Plasma: Indefinite shape and volume. This is a superheated gas, all particle attraction is lost and particles are moving rapidly.
2.
How does matter change state? a.
Matter changes state when energy is added or removed. b.
Matter can freeze (liquid to solid), melt (solid to liquid), boil (liguid to a gas at a specific temperature), evaporate (liquid to gas at the surface of a liquid), condensate (gas to a liquid) or sublimate (solid to gas).
3.
Which phase changes are endothermic? Exothermic? a.
In an endothermic change energy is added. In an exothermic change energy is removed or exits the substance.
4.
What is a pure substance? a.
A pure substance is a substance that is made up of only one particle type. Both elements and compounds are pure substances.

5.
What are elements and compounds? How are they similar? Different? a.
Compounds are pure substances made of two or more atoms/elements. They combine chemically in a specific ratio. b.
Similarities: Both are pure substances c.
Differences: Compounds can be broken down through chemical changes such as adding heat or electric current. Elements cannot be broken down.
6.
What is a mixture? a.
A mixture is a combination of elements and/or compounds that are
NOT chemically combined. Each part of a mixture keeps its identity.
7.
Compare and contrast solutions, colloids and suspensions. a.
All are types of mixtures meaning there are different types of particles physically combined. i.
Solutions: very small particles that are evenly mixed, appears to be one uniform substance and it cannot be filtered (Kool-
Aid) ii.
Colloids: medium sized particles that are large enough to block light but not heavy enough to settle out (mayonnaise, milk, jello) iii.
Suspensions: Large particles that are not well mixed and heavy enough to settle out if left to sit, can usually be filtered (Italian Salad Dressing)
8.
What is the difference between a heterogeneous and homogeneous mixture? a.
Homogeneous mixtures look the same (uniform) throughout the mixture. Heterogeneous mixtures are those mixtures in which you can see individual particles in the mixture.
9.
How can mixtures be separated? a.
Mixtures can be separated through physical means usually distillation, magnetism, or special machines that separates according to weight like the centrifuge.

10.
What are the similarities and differences between elements, compounds and mixtures? a.
All are classifications of matter. Elements are made up of a single atom, compounds are two different elements chemically combined, and mixtures are a combination of elements and compounds physically combined.