1. Properties of Matter
2.1 Classifying Matter

2. Section 2.1: Classifying Matter
Scientists like to classify things.
One way that scientists classify matter is by its composition.
Ultimately, all matter can be classified as mixtures, elements and compounds.

3. Section 2.1: Classifying Matter
Pure Substances
What is Matter? Anything that has mass and takes up space (volume)
Based on matter’s composition, it can be divided into Pure Substances and Mixtures.

4. Can it be separated by physical means?
Matter Flowchart
MATTER
yes no
Can it be separated by physical means?
MIXTURE
PURE SUBSTANCE
Is the composition uniform? no
yes
Can it be decomposed by chemical means? no
yes
Homogeneous Mixture
(solution)
Heterogeneous Mixture
Compound
Element

5. Section 2.1: Classifying Matter
Pure Substances
Def.-matter that always has exactly the same composition (ex. Table salt, table sugar)
Key Concept: Every sample of a given substance has the same properties because a substance has a fixed, uniform composition.
2 Categories of substances: elements and compounds

6. Section 2.1: Classifying Matter
Elements
Def.-a substance that cannot be broken down into simpler substances
Key Concept: An element has a fixed composition because it contains only one type of atom.

7. Section 2.1: Classifying Matter
Elements: Examples of Elements
Carbon (C), Aluminum (Al)- solid at RT
Oxygen (O), Nitrogen (N)- gases at RT
Bromine (Br), Mercury (Hg)- liquid at RT

8. Section 2.1: Classifying Matter
Elements: Symbols for Elements
Developed in 1813 by Swedish chemist Jons Berzelius
Symbols contain 1 or 2 letters
Symbols based on Latin names of the elements
Gold is Au
Aluminum is Al

9. Section 2.1: Classifying Matter
Compounds
Def.-a substance that is made from two or more simpler substances and can be broken down into those simpler substances (elements or other compounds)
H2O→2H + O

10. Section 2.1: Classifying Matter
Compounds
Properties of a compound differ from the properties of the substances from which it is made.
Ex. H and O are gases at room temp.; H2O is liquid at room temp.

11. Section 2.1: Classifying Matter
Compounds
Key Concept: A compound always contains two or more elements joined in a fixed proportion.
Ex. SiO2- 2 (O) atoms for every 1 (Si) atom
Ex. H2O-2 (H) atoms for every 1 (O) atom

12. Section 2.1: Classifying Matter
Mixtures
2 types: heterogeneous and homogeneous
Retain some of the properties of their individual substances
Properties of a mixture are less constant (vary) than the properties of a substance.

13. Section 2.1: Classifying Matter
Mixtures
Key Concept: The properties of a mixture can vary because the composition of a mixture is not fixed.
**Mixtures can be classified by how well the parts of the mixture are distributed throughout the mixture.

14. Section 2.1 Classifying Matter
Mixtures: Heterogeneous and Homogeneous Mixtures
Heterogeneous- the parts of the mixture are noticeably different from one another
Ex. Sand
Homogeneous-the substances are so evenly distributed that it is difficult to distinguish one substance in the mixture from another
Ex. Water, steel

15. Section 2.1 Classifying Matter
Is the mixture uniform throughout?
If the answer is NO, the matter is a heterogeneous mixture.
Considered the “least mixed.”
Does not appear to be the same throughout.
Particles are large enough to be seen and to be separated from the mixture.

16. Section 2.1 Classifying Matter
Is the mixture uniform throughout?
If the answer is YES, the matter is a Homogenous mixture.

17. Can it be separated by physical means?
Matter Flowchart
MATTER
yes no
Can it be separated by physical means?
MIXTURE
PURE SUBSTANCE
Is the composition uniform? no
yes
Can it be decomposed by chemical means? no
yes
Homogeneous Mixture
(solution)
Heterogeneous Mixture
Compound
Element

18. Section 2.1 Classifying Matter
Solutions, Suspensions, and Colloids
The size of the particles in a mixture has an effect on the properties of the mixture.
Key Concept: Based on the size of its largest particles, a mixture can be classified as a solution, a suspension, or a colloid.

19. Section 2.1 Classifying Matter
Solutions
Def.-the mixture that forms when substances dissolve and form a homogeneous mixture
Ex. Sugar water, salt water, lemonade

20. Section 2.1 Classifying Matter
Solutions
*They do not separate into distinct layers over time.
*They cannot be filtered.
*Light passes through them.
The particles in a solution are too small to settle out of the solution, be trapped by a filter, or scatter light.

21. Section 2.1 Classifying Matter
Suspensions
Def.-a heterogeneous mixture that separates into layers over time
Ex. Amoxicillin, Muddy water, Flour suspended in water

22. Section 2.1 Classifying Matter
Suspensions
*Suspended particles settle out of a mixture or are trapped by a filter
They scatter light in all directions because the particles are large; suspensions are cloudy.

23. Section 2.1: Classifying Matter
Colloids
Def.-a mixture that contains some particles that are intermediate in size between the small particles in solution and larger particles in a suspension
Ex. Milk, fog

24. Section 2.1 Classifying Matter
Colloids
Do not separate into layers
Cannot be filtered
Since they also contain larger particles, they scatter light

25. Can it be separated by physical means?
Matter Flowchart
MATTER
yes no
Can it be separated by physical means?
MIXTURE
PURE SUBSTANCE
Is the composition uniform? no
yes
Can it be decomposed by chemical means? no
yes
Homogeneous Mixture
(solution)
Heterogeneous Mixture
Compound
Element