1. Chapter 2

2. Heterogeneous Mixture
Matter
Substance
Element
Compound
Mixture
Heterogeneous Mixture
Colloid
Suspension
Homogeneous Mixture

3. Matter
Definition: Anything that has mass and volume Chemistry is the study of matter and the transformations it undergoes Everything can be classified as matter, energy, or space

4. Transformations of Matter
Physical changes
Some properties of matter change but the composition remains constant
Chemical changes
The composition of matter changes

5. Types of Properties Intensive properties Extensive properties
Based upon the composition of matter
Include
Melting point
Color
Hardness
Extensive properties
Based upon the quantity of matter
Mass
Volume

6. Chemical Changes Chemical changes change the composition of matter.
When matter changes it is called a chemical reaction during which one or more substances are changed to one or more new substances there are several indications a chemical reaction has occurred.

7. Indicators of a Chemical Reaction
Formation of a precipitate
Transfer of Energy
Change of color
Production of a gas

8. Chemical Reaction Fe2O3 + 2Al → 2Fe + Al2O3 + heat
Reactants  Products
Fe2O3 + 2Al → 2Fe + Al2O3 + heat
Chemical reactions take advantage of the chemical properties of a substance to alter its composition. Above is an example of a chemical reaction between iron and aluminum. This specific reaction is known as the thermite reaction and reaches temperatures of over 2500°C.

9. Chemical Properties
Definition: The ability of a substance to undergo a specific chemical change
Mixtures do not have chemical properties, but the substances in mixtures do have chemical properties. Mixtures can be separated based upon chemical properties and compounds (a type of substance) can be separated based on chemical properties

10. Physical changes There are two types of physical changes
Reversible
Irreversible
Reversible changes are most often changes of physical state
Irreversible changes are most often mechanical changes

11. Mechanical Changes
Mechanical changes are usually described as irreversible physical changes. Some of these changes include:
Grinding
Cutting
Breaking
Crushing
All of these actions change the physical nature of matter yet do not change the state or composition of the matter.

12. Physical States Matter exists in 3 major states
Solid
Liquid
Gas
Changes between these three states are always reversible and do not change the composition of the matter
Ex. Icewatersteam (all states of water)

13. Energy Energy is the potential to do work or produce heat
It is easy to confuse energy with sources of energy. The sun produces light and heat which are both forms of energy but the sun itself is made up of matter.

14. Elements
Definition: Simplest form of matter that has unique chemical properties
Elements are homogeneous substances in which every atom of the substance is exactly the same. 94 elements occur naturally on the earth.
Elements are represented by chemical symbols

15. Chemical Symbols A one or two letter abbreviation for the chemical
The first letter is always capitalized the second is always lower case

16. Compounds
Definition: a substance that contains two or more elements chemically combined in a fixed proportion.
Like elements compounds have unique properties and cannot be broken down by physical means, however unlike elements, compounds can be broken down chemically.

17. Fixed Proportions
Fixed proportions means that the ratio of each type of element in a compound must be the same.
Example
H2O is a compound called water
HO is a compound called hydroxide
H2O2 is a compound called peroxide
All of these compounds are made of the same elements but their chemical properties differ greatly

18. Substances
Definition: Substances have uniform and definite composition
Uniform composition means that at any given point in the sample of matter the type of matter present will be exactly the same as any other given point
Definite composition means there is only one way the substance can be made. A molecule of water can only be made with 2 Hydrogen atoms and 1 oxygen atom.

19. Mixtures Definition: A physical blend of two or more components
Matter is classified as a mixture if it fails to meet one or more of the two requirements to be a substance (uniform and definite composition)

20. Homogeneous Mixture (Solutions)
Definition: a mixture in which the composition is uniform throughout
Homogeneous mixtures will have only one phase
Despite only having one phase a mixture is able to be separated by physical processes

21. Phase
Definition – A portion of matter that has uniform composition and properties
but not necessarily definite composition
Phases appear homogeneous to the naked eye

22. Heterogeneous Mixture
Definition: A mixture in which the composition is not uniform throughout
Heterogeneous mixtures have 2 or more phases
The components of a heterogeneous mixture are able to be separated by physical means

23. Colloids
Description: solute particles are small enough to remain mixed and pass through filter paper, but they are visible in a Tyndall test
Often colloids have cloudy or milky appearances
Colloids are in a gray area between homogeneous and heterogeneous but for this class they will be considered heterogeneous

24. Suspensions
Description: have larger particles which settle out over time and can be filtered out of the mixture
Classified as a heterogeneous mixture

25. Tyndall test
They Tyndall effect (Tyndall Test) occurs when a beam of light is passed through a mixture. If the light is scattered as it passes through the mixture it tests “positive” for the Tyndall effect
A positive result indicates a colloid
Light scattering gives mixtures the appearance of glowing