Download presentation
Presentation is loading. Please wait.
2
What is a Physical Change?
A physical change alters the form of a substance, but does not change it to another substance. Example: Making Orange Juice
3
What is a Chemical Change?
When a substance undergoes a chemical change, it is changed into a different substance with different properties. Example: Baking a Cake
4
Chemical or Physical Change?
Rocket fuel burning? Chemical
5
Chemical or Physical Change?
Metal rusting? Chemical
6
Chemical or Physical Change?
Disappearing puddle? Physical
7
Chemical or Physical Change?
Candle burning? Chemical
8
Chemical or Physical Change?
Dry ice? Physical
9
5 Signs of a Chemical Change
Color Change Precipitation
10
Precipitation Precipitation – the solid that forms from a solution during a chemical reaction. It looks like a cloudy solid in an otherwise clear solution.
11
5 Signs of a Chemical Change
Gas Production Temperature Change
12
5 Signs of a Chemical Change
Changes in Characteristic Properties (odor, light given off)
13
Physical and Chemical Properties
14
Anything that has mass and takes up space!
Matter Anything that has mass and takes up space!
15
Mass A measure of how much matter is in an object.
16
Weight A measure of the force of gravity on an object.
17
Volume The amount of space that matter occupies.
18
Density The measurement of how much mass of a substance is contained in a given volume. Mass/Volume I Density
19
States of Matter There are different “states” of matter. States of matter are also known as phases (a physical state of matter). Elements and compounds can move from one phase to another phase when special physical forces are present. Solid Liquid Gas
20
What are properties? Matter has observable and measurable qualities.
We can use general properties to identify substances. Two basic types of properties of matter: Physical properties and Chemical properties:
21
Freezing point The temperature at which a liquid changes into a solid.
22
Boiling point The boiling point of an element or compound means the temperature at which the liquid form of an element or compound turns into a gas the boiling point of water is 100 degrees Celsius.
23
Melting point The temperatures at which the solid form of the element or compound turns into a liquid. Basically the range at which the solid changes its state into a liquid. The melting point of water is 0 degrees Celsius
24
Physical Properties Physical properties are used to identify, describe and classify matter. Characteristic of a substance that can be observed (using your senses) without changing the substance into something else. Hardness Texture Color Odor Taste Temperature
25
More EXAMPLES - Physical
size, shape, freezing point, boiling point, melting point, magnetism, viscosity, density, luster and many more. Viscosity - The resistance of a liquid to flowing. Examples: Low viscosity-water, rubbing alcohol High viscosity-honey
26
Creating a new chemical product
Chemical Properties Chemical properties are characteristics involved when a substance interacts with another substance to change its chemical make-up. Flammability Rusting Creating gas bubbles Creating a new chemical product Reactivity with water pH
27
Mixtures, Elements and Compounds
A Matter of Fact Mixtures, Elements and Compounds
28
Elements, Compounds, and Mixtures
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.
29
Why isn’t it a good idea to classify matter by its phases?
Because one kind of substance can exist in more than one phase – such as H20. And matter changes phases rather easily.
30
Why isn’t matter classified according to its physical characteristics, such as color?
Scientists wouldn’t find it very useful to group gold, sunflowers, and the sun together.
31
Scientists ask themselves these questions?
Is the matter uniform throughout? Can it be separated by physical means? Can it be separated by chemical means?
32
Elements Compounds Mixtures
By asking these questions scientists can classify matter into: Elements Compounds Mixtures
33
Sample of the Element Lead Sample of the Element Chlorine
Elements Made up of one type of atom Cannot be broken down by physical and chemical methods Examples: Oxygen, Nitrogen, Carbon Sample of the Element Lead Sample of the Element Chlorine
34
Compounds Form when two or more different elements join (bond) together chemically Composition is identical in each sample Can be separated only by chemical methods Properties of a compound are totally different than the properties of the elements that form them Examples: Water, Carbon dioxide, Sugar
35
Compounds
36
Mixtures Form when elements and/or compounds are combined physically
Composition varies from sample to sample Can be separated by physical methods Examples of Mixtures: Tea, Perfume, Air, Salad, Beach sand, oil and vinegar salad dressing, etc.
37
Mixture of Different Elements Mixture of Different Compounds
Mixtures Mixture of Different Elements Mixture of Different Compounds
38
Mixtures are often referred to as homogeneous or heterogeneous.
39
Mixtures Homogeneous mixtures (Solutions) have a uniform distribution.
For example: Tea, Perfume, Air, Salt Water, Coffee
40
Mixtures Heterogeneous mixtures do not have a uniform distribution.
Parts are often visible For example: Salad, Beach Sand, Oil and Vinegar dressing
41
Distinguishing between Elements, Compounds, and Mixtures
42
Distributed Summarizing
The diagram below shows how two elements can be mixed together…Which is a Compound? A Mixture? A. B. C. D. Compound Mixture
43
Heterogeneous Mixtures
If you can clearly tell that there is more than one thing in a container it’s heterogeneous If you can tell there is an easy way to separate things then it’s a heterogeneous mixture.
44
Examples of heterogeneous mixtures
Sand and pebbles Oil and water
45
Granite is a heterogeneous mixture.
46
Homogeneous Mixtures A mixture that appears to be the same throughout.
It is “well mixed.” The particles that make up the mixture are very small and not easily recognizable.
47
Examples of homogeneous mixtures
Milk, toothpaste, and mayonnaise are homogeneous mixtures.
48
Solutions A solution is a type of homogeneous mixture formed when one substance dissolves in another. It is the best mixed of all mixtures. A solution always has a substance that is dissolved and a substance that does the dissolving. The substance that is dissolved is the solute and the substance that does the dissolving is the solvent.
49
Ocean water is a solution
50
The universal solvent: Water
51
Water as a solvent Many liquid solutions contain water as the solvent.
Ocean water is basically a water solution that contains many salts. Tea and coffee are both water solutions also
52
Metric System Basics
53
Metric System The metric system is based on a base unit that corresponds to a certain kind of measurement Length = meter Volume = liter Weight (Mass) = gram Prefixes plus base units make up the metric system Example: Centi + meter = Centimeter Kilo + liter = Kiloliter
54
Metric System The three prefixes that we will use the most are: kilo
centi milli kilo hecto deca Base Units meter gram liter deci centi milli
55
Metric System So if you needed to measure length you would choose meter as your base unit Length of a tree branch 1.5 meters Length of a room 5 meters Length of a ball of twine stretched out 25 meters
56
Metric System But what if you need to measure a longer distance, like from your house to school? Let’s say you live approximately 10 miles from school 10 miles = meters 16093 is a big number, but what if you could add a prefix onto the base unit to make it easier to manage: 16093 meters = kilometers (or 16.1 if rounded to 1 decimal place)
57
Metric System These prefixes are based on powers of 10. What does this mean? From each prefix every “step” is either: 10 times larger or 10 times smaller For example Centimeters are 10 times larger than millimeters 1 centimeter = 10 millimeters kilo hecto deca Base Units meter gram liter deci centi milli
58
Metric System Centimeters are 10 times larger than millimeters so it takes more millimeters for the same length 1 centimeter = 10 millimeters Example not to scale 40 41 1 mm 40 41 1 cm
59
Metric System For each “step” to right, you are multiplying by 10
For example, let’s go from a base unit to centi 1 liter = 10 deciliters = 100 centiliters 2 grams = 20 decigrams = 200 centigrams ( 1 x 10 = 10) = (10 x 10 = 100) (2 x 10 = 20) = (20 x 10 = 200) kilo hecto deca meter liter gram deci centi milli
60
Metric System An easy way to move within the metric system is by moving the decimal point one place for each “step” desired Example: change meters to centimeters 1 meter = 10 decimeters = 100 centimeters or 1.00 meter = 10.0 decimeters = 100. centimeters kilo hecto deca meter liter Gram deci centi milli
61
Metric System Now let’s try our previous example from meters to kilometers: 16093 meters = decameters = hectometers = kilometers So for every “step” from the base unit to kilo, we moved the decimal 1 place to the left (the same direction as in the diagram below) kilo hecto deca meter liter gram deci centi milli
62
Metric System If you move to the left in the diagram, move the decimal to the left If you move to the right in the diagram, move the decimal to the right kilo hecto deca meter liter gram deci centi milli
63
Metric System Now let’s start from centimeters and convert to kilometers centimeters = 4 kilometers centimeters = kilometers kilo hecto deca meter liter gram deci centi milli
64
Metric System Now let’s start from meters and convert to kilometers
4000 meters = 4 kilometers kilo hecto deca meter liter gram deci centi milli Now let’s start from centimeters and convert to meters 4000 centimeters = 40 meters kilo hecto deca meter liter gram deci centi milli
65
Metric System Now let’s start from meters and convert to centimeters
5 meters = 500 centimeters kilo hecto deca meter liter gram deci centi milli Now let’s start from kilometers and convert to meters .3 kilometers = 300 meters kilo hecto deca meter liter gram deci centi milli
66
Metric System Now let’s start from kilometers and convert to millimeters 4 kilometers = millimeters or 4 kilometers = 40 hectometers = 400 decameters = 4000 meters = decimeters = centimeters = millimeters kilo hecto deca meter liter gram deci centi milli
67
Metric System Summary Base units in the metric system are meter, liter, gram Metric system is based on powers of 10 For conversions within the metric system, each “step” is 1 decimal place to the right or left Using the diagram below, converting to the right, moves the decimal to the right and vice versa kilo hecto deca meter liter gram deci centi milli
Similar presentations
