1. CH. 2.1
MATTER AND CHANGE

2. CH. 2.1 DESCRIBING MATTER Observation: using your senses to describe.
White, waxy substance
Inference: making a conclusion
made of wax.

3. DESCRIBING MATTER Qualitative: describing matter using the senses.
White, smooth, circular, smells like flowers, warm
Quantitative: numerically descriptive
8.5 cm high, weighs 85 grams.

4. DESCRIBING MATTER
Extensive Property: depends on the amount of the sample. (can vary from sample to sample even if same substance)
Weight, volume, height, shape
Intensive Property: depends on type (composition) of substance. (doesn’t change as long as samples are made of same substance)
Color, melting point, reaction with other things

5. GIVE EXAMPLES OF EXTENSIVE AND INTENSIVE PROPERTIES OF THESE 2 SAMPLES OF SILICON

6. IDENTIFYING SUBSTANCES
Physical Property: quality/condition of substance that can be observed or measured w/o changing substance.
Color, weight, size, volume ,

7. IDENTIFYING SUBSTANCES
Physical Change: changing the state but not the composition.
Melting, boiling, vaporizing, freezing, crushing, dissolving

8. IDENTIFYING SUBSTANCES
Chemical Property: how a substance react with another substance.
Iron reacts with oxygen.

9. Chemical Change: the reaction that takes place when two substances react (Chemical Reaction). Composition changes. (observe bubbling, color change, precipitate)
Iron reacts with oxygen to make rust.

10. COMMON STATES OF MATTER
Solid: definite shape and volume
Liquid: indefinite shape, flows, definite volume.
Gas (Vapor): indefinite shape and volume, flows.

11. Mixtures, Elements, CompoundsCh
Mixtures, Elements, Compounds

12. Symbols Chemists use chemical symbols to represent elements
Chemical Symbol: 1st 1-2 letters of the name of the element
1st letter is always Capitalized
2nd letter is always lower case
Examples: Co = Cobalt; O = Oxygen;
Be = Berylium
Exception: Some use the letters from the Latin name
Examples: Fe = Iron (Ferrum)
K = Potassium (Kalium)
Cu = Copper (Cuprium)

13. Formulas Chemists use chemical formulas to represent compounds
Compounds: 2 or more elements
Examples: NaCl = Sodium Chloride
H2O = Water

14. Breaking up
Compounds can be broken down into simpler substances by chemical means, but elements cannot
Chemical changes can be used to break down the substances
Heating sugar can be heated until it breaks down into solid carbon and water vapor

15. Properties
Properties of compounds differ greatly from the properties of the individual elements that make them up
Solid sodium is extremely reactive
Chlorine is a gas
Combined they make up sodium chloride, aka table salt

16. Na + Cl2 → NaCl Sodium + Chlorine → Table salt

17. H2 + O2 → H2O

18. Classifying mixtures
A mixture is a physical blend of two or more components
Based on the distribution of the components, mixtures can be classified as heterogeneous or homogeneous mixtures

19. Heterogeneous mixture: a mixture in which the composition is not uniform throughout
Ex: oil and vinegar, sand in water
Homogeneous mixture: a mixture in which the composition is uniform throughout
Also known as a solution

20. Homogeneous mixtures
Many solutions are liquid, but can also be gas (air) or solids (stainless steel)
The term “phase” can be used to describe any part of a sample with uniform composition and properties
Homogeneous mixtures have 1 phase

21. Heterogeneous V. Homogeneous

22. Distinguishing Substance and Mixtures
Matter
Substance:
Definite Composition
(Homogeneous)
Mixture
of Substance:
Variable Composition
Element
Ex: Sodium Na
Compound
Ex: Sodium Chloride
Homogeneous
Mixture:
Uniform; also called
a Solution
Ex: Salt in Water
Heterogeneous
Non-uniform;
Distinct phases
Ex: Milk

23. Separating mixtures
Different physical properties can be used to separate mixtures
Different BPs or MPs can be used
Filtration: separates a solid from a liquid
Coffee filters separate grounds from water
Distillation: a liquid is boiled to produce a vapor then condensed into a liquid

25. Paper chromatography Separating a mixture

26. Chemical reactions
Chemical changes are signs of chemical reactions happening
Iron reacting with oxygen to form rust
Fe + O2 → Fe2O3
During a chemical reaction, the composition of matter always changes

27. A substance produced in the reaction is the “product”
Fe + O2 → Fe2O3
Reactants Products
A substance present at the start of a chemical reaction is called a “reactant”
A substance produced in the reaction is the “product”
Reactants react to produce products

28. Recognizing chemical reactions
Signs a reaction may have occurred:
Production of gas or bubbles
Change in color
Change in temperature
Precipitate forms
A solid that forms and settles out of a liquid mixture

29. Law of Conservation of Mass
During any chemical reaction or physical change, the mass of the products is always equal to the mass of the reactants
Bottom line: you cannot create or destroy matter. Matter is conserved.