1. DESCRIBE PHYSICAL & CHEMICAL CHANGES IN TERMS OF ENDOTHERMIC & EXOTHERMIC PROCESSES
COS 5.0

2. WHAT YOU’LL LEARN
Explain the relationship between, matter atoms & elements
Categorize materials as pure substances or mixtures
Identify elements & compounds
Perform calculations involving density
Compare & Contrast physical & chemical properties
Determine how the law of conservation of mass applies to chemical changes
Compare & Contrast physical & chemical changes
Describe how to detect whether a chemical change has taken place.
Describe the four common states of matter.
List the different changes of state & describe how particles behave in each state
Describe differences between endothermic & exothermic reactions

3. MATTER

4. COMPOSITION MATTER anything that has mass and takes up space (volume)
ATOMS
smallest particle of an element that has same properties of element
MOLECULES
smallest unit of a substance that keeps all of physical and chemical properties of that substance.
Two or more atoms that are chemically bonded

5. CLASSIFICATION

6. PURE SUBSTANCE
sample of matter, either a single element or a single compound, that has definite chemical and physical properties

7. ELEMENTS
substance that cannot be separated or broken down into simpler substances by chemical means
Can be found as solids, liquids, or gases
Found on periodic table
Made of identical atoms
Pure substances
Represented by abbreviations/symbols consisting of one or two letters
Examples: H, N, S, O, P, Au, Hg, Na

8. COMPOUNDS
substance made of atoms of two or more different elements that are chemically combined
they always combine in same proportions.
Can be broken down through chemical means
Pure substances
Every compound is different from the elements it contains.

9. CHEMICAL FORMULAS
combo of chemical symbols and numbers to represent a substance.
Subscript
represents number of atoms
located lower right of chemical symbol
Examples: NO2, NH3, NaCl, C6H6O6

10. MIXTURES two or more substances that are NOT chemically combined.
Variable composition
Each components retains their characteristic properties
May be separated into pure substances by physical methods
classified by how thoroughly the substances mix.
Two types

11. HOMOGENEOUS may be pure substances or solutions
Pure substances may be compounds or elements
substances are evenly distributed “well mixed”
Look/have the same composition throughout
Particles are small and not easily recognized
can be separated by physical means (dissolution, centrifuge, gravimetric filtering, etc.).
Examples: milk, yogurt

12. HETEROGENEOUS made of more than one kind of substance.
substances aren’t mixed uniformly “least mixed”
different particles in mixtures are large enough to be seen
easily separated by physical means (ie. density, polarity, metallic properties).

13. 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

14. PROPERTIES OF MATTER

15. PHYSICAL PROPERTIES
characteristic of matter that can be directly observed without changing identity of substance
you can see, such as color, shape, hardness, and texture
easily measured

16. MASS
amount of matter in an object
SI Unit: G r a m s (g)

17. WEIGHT measure of pull of gravity on an object
SI Unit: N e w t o n s (N)
Formula: W = m g

18. VOLUME amount of space taken up by an object .
SI Unit: L i t e r s (L).

19. DENSITY
mass per unit of volume
Formula: Density = mass/volume

20. D = M V D M V

21. D M V Density V = 825 cm3 M = DV D = 13.6 g/cm3
1. An object has a volume of 825 cm3 and a density of 13.6 g/cm3. Find its mass.
GIVEN:
V = 825 cm3
D = 13.6 g/cm3
M = ?
WORK:
M = DV
M = (13.6 g/cm3)(825cm3)
M = 11,220 g D M V

22. D M V Density D = 0.87 g/mL V = M V = ? M = 25 g V = 25 g 0.87 g/mL
2. A liquid has a density of 0.87 g/mL. What volume is occupied by 25 g of the liquid?
GIVEN:
D = 0.87 g/mL
V = ?
M = 25 g
WORK:
V = M D D M V
V = g
0.87 g/mL
V = 28.7 mL

23. D M V Density M = 620 g D = M V = 753 cm3 D = ? D = 620 g 753 cm3
3. You have a sample with a mass of 620 g & a volume of 753 cm3. Find density.
GIVEN:
M = 620 g
V = 753 cm3
D = ?
WORK:
D = M V D M V
D = g
753 cm3
D = 0.82 g/cm3

24. Let’s Try Some More Density Problems

25. D M V Density M = 500 g D = M V = 25 cm3 D = ? D = 500 g 25 cm3
1. If the mass of a rock is 500 g and its volume is 25 cm3, what is its density?
GIVEN:
M = 500 g
V = 25 cm3
D = ?
WORK:
D = M V D M V
D = g
25 cm3
D = 20 g/cm3

26. D M V Density V = 10 ml M = DV D = 1.2 g/ml M = (1.2 g/ml)(10 ml)
2. If the density of a liquid is 1.2 g/ml and its volume is 10 ml, what is its mass?
GIVEN:
V = 10 ml
D = 1.2 g/ml
M = ?
WORK:
M = DV
M = (1.2 g/ml)(10 ml)
M = 12 g D M V

27. D M V Density D = 1.6 kg/l V = M V = ? M = 80 kg V = 80 kg 1.6 kg/l
3. If Bob’s mass is 80 kg and his density is 1.6 kg/l, what is his volume?
GIVEN:
D = 1.6 kg/l
V = ?
M = 80 kg
WORK:
V = M D D M V
V = kg
1.6 kg/l
V = 50 mL

28. BOILING POINT temperature and pressure at which a liquid becomes a gas
liquid is still the same substance

29. MELTING POINT
temperature and pressure at which a solid becomes a liquid

30. VISCOSITY resistance (difficulty) of a liquid to flow easily
How “thick” or “thin” a liquid is
high viscosity: Honey, motor oil, corn syrup
low viscosity: water, milk, soda

31. CONDUCTIVITY ability to conduct heat or an electric current
High conductivity: metals (copper, aluminum…)
Low conductivity: wood, rubber, plastic

32. MALLEABILE
Ability to be hammered into a thin sheet.

33. DUCTILE
Ability to be drawn into a thin wire

34. CHEMICAL PROPERTIES
describes how a substance can change or react to form new substances.

35. FLAMMABILITY
ability of a substance to react in presence of oxygen and burn when exposed to a flame

36. REACTIVITY
how easily a chemical reacts with other substances.

37. CHANGES OF MATTER

38. LAW OF CONSERVATION OF MATTER
matter cannot be created nor destroyed.
It is just converted from one form to another

39. STATES OF MATTER

40. SOLIDS Have a definite shape Have a definite volume
Least amount of movement of particles.
Particles arranged in a regular pattern and tightly packed.

41. LIQUIDS Have an indefinite shape Have a definite volume
will assume the shape of its container.
Particles are close together but move about freely.

42. GASES Have an indefinite shape Have an indefinite volume
Can fill any container

43. PLASMA most common form of matter.
makes up over 99% of the visible universe
dangerous, very high energy (found in stars)

44. ENDOTHERMIC/EXOTHERMIC REACTIONS
Endothermic = heat energy is absorbed, cools surroundings
Exothermic = heat energy is released, warms surroundings

45. PHYSICAL CHANGES
substance changes state but does not change its chemical composition.
Type of matter remains the same
example: water freezing into ice, cutting a piece of wood into smaller pieces

46. DISSOLVING to disintegrate, break up, or disperse
When a substance dissolves, the molecules of the substance do not change.
Ways of Dissolving:
solid in a liquid,
gas in a liquid
liquid in a liquid

47. MELTING
to become altered from a solid to a liquid state usually by heat
endothermic
ice cubes melting

48. BOILING Change of a substance from a liquid to a gas. endothermic
two types:
Boiling:
rapid
gas bubbles are produced throughout
Evaporation
slow
occurs at the surface
is a cooling process
ocean water evaporates to form clouds & rain droplets

49. CONDENSATION Change of a gas to a liquid. exothermic
water vapor turns into dew

50. SUBLIMATION
Changing directly from solid to gas or gas to solid skipping the liquid state.
endothermic
formation of frost/snow & dry ice

51. FREEZING Changing from a liquid to a solid.
Particles lose kinetic energy and slow down.
exothermic
water turns to ice

52. CHEMICAL CHANGES
change of a substance into a new and different substance
aka chemical reaction
cannot be reversed by physical changes.
impossible to “unbake” a cake.

53. CHEMICAL REACTIONS
Reactants: are the substances that enter a chemical reaction
Products: are the substances formed by a chemical reaction

54. CHARACTERISTICS & EXAMPLES OF CHEMICAL CHANGES
Reaction with acids Digestion, fizzing
Reaction with oxygen (combustion) Explosions, Burning
Ability to act as oxidizing agent Rusting
Reaction with other elements production of heat, sound, light
Decomposition into simpler substances change of smell, Decomposing
Corrosion water lines becoming thin
Change in color -----Baking food
Production of a gas Fermentation