1. Pure Substances vs. Mixtures Physical and Chemical Changes
What's the "Matter"?
Pure Substances vs. Mixtures
Physical and Chemical Changes

2. Everything that has mass and takes up space is called matter.
What is matter?
Everything that has mass and takes up space is called matter.
Basic definition of matter.

4. There are 2 types of matter:
Pure Substances
Mixtures

5. There are two kinds of pure substances
Elements
Compounds

6. What are "pure substances"?
Matter that has a fixed composition and definite properties. (chemical and physical)

7. Elements
Substance that cannot be separated or broken down into simpler substances by chemical means.
Ex’s- any box on the periodic table
Made of only 1 type of atom
The smallest unit of an element that
maintains the properties of that element
HUH?

8. The smallest unit of an element that maintains the properties of that element???
The element sodium has certain properties
11 protons, 11 electrons…boiling point, etc

9. Compounds cont…
Substance made of atoms of 2 or more different elements that are CHEMICALLY combined.
Elements are combined in a definite way and this changes their properties
Na- lethal if ingested Cl- lethal if ingested
NaCl- table salt

10. Molecules Two or more atoms bonded together… Ex- O2, NaCl, etc.
Not all molecules are compounds, but all compounds are molecules…explain

11. What is a pure substance?
Compounds
Molecules made by two or more elements bonded together -always in a definite ratio
Elements
Molecules made of just one element
The two categories of pure chemical substances.
Na (sodium)
NaCl (sodium chloride/salt)

12. Characteristics of Pure Substances
Cannot be separated into simpler substances by physical methods (physical changes)
Fixed composition
Properties do not vary
Can be expressed with a chemical formula
Ex H2O, NaCl, H
Basic characteristics of pure substance:

14. What is a mixture?
Mixtures are two or more substances that are physically combined.
(NOT chemically combined like a pure substance)
May be separated into pure substances by physical methods

15. Examples of Mixtures

16. Characteristics of Mixtures
Components retain their characteristic properties and can be separated by physical means.
Basic identification of a mixture.
This sand and iron filings mixture can be separated using a magnet.

17. Two types of mixtures

18. Homogenous Mixtures Homogenous mixtures look the same throughout
Types: solutions, alloys, etc.
Example: salt water, brass

19. Indicators of Homogenous Mixtures
Have the same composition throughout
Components are indistinguishable
Will not scatter light
Particle size is small
Brainstorm more examples of homogenous mixtures.

20. Can they still be separated by physical means ?
YES!!! It may be more complicated, but it can be done…distillation , centrifugation

21. Homogeneous mixtures are
called solutions
Solutions are …
homogenous mixtures that do not scatter light.
separated by physical means (including distillation or evaporation.)
created when something is completely dissolved in pure water.
Examples: sugar water, salt water

22. Parts of a Solution Solute- substance that dissolves in solvent
ex. Salt (“U dissolve”)
Solvent- substance that does the dissolving (ex.water)
Well, not really, because you don’t dissolve, but you get the picture 

23. Why don’t you dissolve? You are not “Miscible”
Miscible- two or more liquids that can dissolve into each other
Immiscible- liquids that do NOT mix
Ex- oil and water

24. Heterogenous Mixtures
Heterogeneous mixtures are composed of large pieces that are easily separated by physical means (ie. density, polarity, metallic properties).

25. Indicators of Heterogenous Mixtures
Do not have same composition throughout
Components are distinguishable
Particle size is medium or large
Examples: fruit salad, vegetable soup, etc.
Brainstorm more examples of heterogenous mixtures.

26. Tyndall Effect
Scattering of light due to particles

27. Heterogenous Mixtures
Types of
Heterogenous Mixtures
1. Colloid –medium particles
Particles stay suspended in the mixture and scatter light (Tyndall effect)
Ex- mayonnaise, milk, fog

28. Heterogenous Mixtures
Types of
Heterogenous Mixtures
1. Suspension- large particles
Tyndall effect
Particles will settle out when the mixture is allowed to stand
Ex-muddy water, OJ with pulp

29. physical properties
Physical properties are those that we can determine without changing the identity of the substance we are studying.
Properties we can observe or measure
Ex- color, state of matter, etc

30. DENSITY
Mass per unit volume
Calculated by:
Density= Mass/Volume
D=M/V

31. Examples of physical properties:
Hardness, color, melting point and density are all physical properties.
The physical properties of sodium (NaCl) metal
soft, lustrous
silver-colored metal
relatively low melting point
low density.

32. Chemical and Physical Properties

33. Physical Properties
Physical properties can be determined without changing the identity of the substance.
Examples???

34. Viscosity Resistance to flowing Maple Syrup- High Viscosity
Water- Low Viscosity

35. Ductility
Ability to be drawn into a thin wire

36. Malleability
Ability to be hammered into thin sheets without shattering

37. Hardness
A substance’s resistance to being scratched

38. Solubility Ability to dissolve in water
Yes! It is a physical property because you do not need to alter identity of the substance to determine solubility.

39. Ability to carry electricity
Conductivity
Ability to carry electricity
High Conductivity (the liquid is able to let electrons flow to complete the circuit
Low Conductivity (the liquid is NOT able to let electrons flow to complete the circuit

40. What is a superconductor?
Watch this video and try to write a one sentence definition.

41. Video on Superconductors

42. Other examples of physical properties….
boiling point
shape
density
freezing point
melting point
temperature

43. Chemical Properties
Describe the way a substance can change or react to form other substances.
(NOT the actual reaction- that’s a chemical __________)
Must be determined using a process that changes the identity of the substance

44. How can chemical properties be identified?
One of the chemical properties of alkali metals such as sodium and potassium is that they react with water. To determine this, we would have to combine an alkali metal with water and observe what happens.
In other words, we have to define chemical properties of a substance by the chemical changes it undergoes.

45. Ex’s of Chemical Properties
Reactivity: ability of a substance to combine CHEMICALLY (at the electrons) with another substance (to form a compound)

46. Flammability
Ability of a material to burn in the presence of Oxygen.

47. Alkalinity
Ability to neutralize acids

48. What is a physical change?
A change that does not change the chemical composition of a substance.
Ex: changes in size, shape, appearance, etc.
Why? The form or appearance has changed, but the properties of that substance are the same (i.e. it has the same melting point, boiling point, chemical composition, etc.)
Definition of physical changes.

49. Physical Changes PHYSICAL CHANGE: Changes in Temperature
Melting, Boiling, Freezing
Changes in Color
Conducting electricity
Dissolving
Hammering into a sheet
Drawing into a wire
PHYSICAL PROPERTY
Melting Point, Boiling Point, Freezing Point
Color
Conductivity
Solubility
Malleability
Ductility
Physical changes are characterized by the following:

50. What are chemical changes?
A chemical change occurs when a substance changes into something new.
This occurs due to heating, chemical reaction, etc.
You can tell a chemical change has occurred if the density, melting point or freezing point of the original substance changes. Many common signs of a chemical change can be seen (bubbles forming, mass changed, etc).
Definition of chemical change.

51. How to recognize a chemical change
Recall: A chemical change occurs when a substance changes into something new.
Foaming
Bubbles
New odor
Heat production or drop in temperature
New precipitate (solid formed from liquids)
Definition of chemical change.

52. Characteristics of Chemical Changes
Baking soda reacting w/ vinegar
You can’t go back to the original substances after a chemical change (reaction) has occurred!!
Chemical Changes are characterized by the following:
Burning wood

53. Comparison of Physical and Chemical Properties

54. Conservation of Matter
Law of
Conservation of Matter
There is no observable change in the quantity of matter during a chemical reaction or a physical change.
In other words, matter cannot be created nor destroyed. It is just converted from one form to another
Definition of Conservation of matter.

55. Answers to bottom of notes…
Photosynthesis
Burning charcoal
Breaks easily
Fizzes with vinegar
Tea kettle boiling
Digestion of food
Painting a house
Grinding meat into hamburger
Reacts with air
Has a sour odor
Chemical Change
Physical Property
Chemical Property
Physical Change

56. Physical Properties of Matter
Property
Description
Example
Hardness
Ability of 1 substance to scratch another
Diamond can scratch glass
Viscosity
Resistance to flowing
Water= low visc.
Honey= high visc.
Solubility
Ability to dissolve in water
NaCl dissolves easily in water so it’s soluble

57. Physical Properties of Matter
Property
Description
Example
Superconductor
Substance that conducts electricity at lower temperatures
Tin, aluminum, used in trains
Semiconductor
Substance that has a resistance b/w a conductor & insulator
Silicon-used in computers or radios

58. Physical Properties of Matter