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Introduction to Chemistry

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Title: Introduction to Chemistry


1
Introduction to Chemistry
  • Chapter 1

2
Chemistry and Matter
  • Chemistry is the study of matter and the changes
    that it undergoes.

3
Matter and its Characteristics
  • Matter anything that has mass and takes up
    space.

4
Matter and its Characteristics
  • Mass and Weight
  • Mass the amount of matter that makes up an
    object.
  • Weight the amount of matter in an object AND
    the effect of Earths gravitational pull on that
    matter.
  • The mass of an object DOES NOT change with
    location
  • The weight of an object DOES change if the force
    of gravity changes. (Things weigh less on the
    moon because the moons gravity is lower than
    earths.)

5
Scientific Method
  • The Scientific Method is an organized plan used
    to gather, organize and share information.

6
Scientific Method
Make an Observation (Ask a Question) Uses the
senses (sight, hearing, taste, touch, smell)
7
Scientific Method
  • Develop a Hypothesis
  • A Prediction
  • An educated guess
  • Developed in an attempt to answer a question.
  • Must be testable.

8
Scientific Method
  • Test the Hypothesis
  • Perform an Experiment, gather data.
  • Qualitative Data information that describes
    color, odor, shape, or some other physical
    characteristic.
  • Quantitative Data numerical information telling
    how much, how little, how fast, etc.

9
Scientific Method
Analyze Data
10
Scientific Method
Draw Conclusions
11
Scientific Method
If the data does not support the hypothesis,
revise (change) the hypothesis.
12
Scientific Method
Develop a Theory
13
Scientific Method
  • Theory
  • Developed after MANY, MANY experiments have
    supported the hypothesis
  • Explains the question or observation.

14
Scientific Method
Whats the difference between a Scientific
Theory and a Scientific Law?
15
Scientific Method
Theory Explains the question or observation
weve made.
16
Scientific Method
  • Scientific Law
  • Summarizes a pattern found in nature
  • Does NOT explain the observation or question.

17
Experimentation
Controlled Experiment In a controlled
experiment, there are two groups
Control Group a group or material that all
conditions (except the independent variable) are
identical to the experimental group.
18
Experimentation
Controlled Experiment In a controlled
experiment, there are two groups
Experimental Group the group or material
with which you are deliberately changing the
independent variable.
19
Experimentation
In an experiment, there are two variables
  • Independent Variable the condition that is
    controlled (and changed) by the scientist
    Manipulated Variable. Graphed on the X-Axis of a
    graph.
  • Dependent Variable the result of the change in
    the independent variable. Graphed on the Y-Axis
    of a graph.
  • Remember In a controlled experiment, Only ONE
    independent variable is changed at a time.
  • Independent Variable
  • Dependent Variable

20
Types of Research
  • Pure Research Research that seeks only to gain
    knowledge.
  • Applied Research Research that seeks to solve a
    problem.

21
Technology
  • Technology is the practical use of scientific
    information. It is used to make improvements in
    human life and the world around us.

22
Data Analysis
  • Chapter 2

23
Units of Measurement
  • Scientists are able to communicate
    internationally because they all use the same
    units the International System of Units (SI).

24
Metric (SI) Prefixes
After you learn the base units, you need to
understand the prefixes.
Example 1 kilogram means 1000 grams.
25
Volume
  • Volume is how much space an object takes up.
  • The metric unit for volume we normally use in
    chemistry is the Liter. A liter is approximately
    equal to one quart.
  • 1 L 1 dm3
  • 1 ml 1 cm3

26
Density
  • Density is mass divided by volume.

Units g/cm3
  • Density of water is 1 g/cm3

27
Density Lab
Required Materials
Triple-beam balance Graduated Cylinder cm
Ruler water Objects to be measured
28
Temperature
  • In science we use two Temperature Scales
  • Celsius Scale uses the freezing point and
    boiling point of water.
  • Freezing point of water 0C
  • Boiling point of water 100C
  • Kelvin Scale uses absolute zero
  • K C 273
  • Freezing point of water 273 K
  • Boiling point of water 373 K

29
Scientific Notation
In science, we sometimes use very large or very
small numbers. These numbers are hard to write
so
We use Scientific Notation to make writing these
numbers easier.
30
Scientific Notation
  • Multiplying Exponents
  • (1 x 103) x (2 x 104)

You multiply the first numbers (1 x 2)
and add the exponents (3 4).
(1 x 2) x 10(34)
2 x 107
31
Scientific Notation
  • Dividing Exponents
  • (1 x 103) (2 x 104) first, lets rewrite it

1 x 103
2 x 104
You divide the first numbers (1/2) and subtract
the exponents (3 - 4).
1 X 10 (3-4)
2 X 10 (3-4)
.5 x 10-1
5 x 10-2
32
Significant Figures
  • The precision of the instruments used determines
    how exact your data is and determines the number
    of significant figures in your calculations.
  • Significant figures include all known digits plus
    one estimated digit.

33
Significant Figures
  • Rules for Significant Figures
  • Non-Zero numbers are always significant.
    72.3 g has 3
  • Zeros between non-zero numbers are significant.
    60.5 g has 3
  • All final zeros to the right of the decimal place
    6.20 g has 3are significant.
  • Zeros that are placeholders are NOT significant.
    0.0253 has 3
    4320
    has 3

34
Tables and Graphs
  • Data is also presented in graphs.

Types of graphs Bar graphs Line graphs Circle
graphs
35
Tables and Graphs
  • Bar Graphs are often used to compare sets of data.

36
Tables and Graphs
  • Circle Graphs are often used to show how one part
    compares to the whole.

37
Tables and Graphs
  • Line Graphs are often used to show how one
    variable changes in response to another.

38
Tables and Graphs
  • The slope on line graphs can also give us
    information.

The slope of a line is rise over run.
Slope 3 g/ml
The slope of this line tells us density!
39
Tables and Graphs
  • Graphs need to have the following labels
  • Dependent Variable on Y-Axis
  • Y-Axis Title
  • Y-Axis Units
  • Independent Variable on X-Axis
  • X-Axis Title
  • X-Axis Units
  • Graph Title
  • Reasonable graph

40
Matter Properties and Changes
  • Chapter 3

41
Properties of Matter
  • Substance (also known as a Pure Substance)
    matter that has a uniform and unchanging
    composition.
  • Water is a substance H2O each atom of water is
    always made up of two Hydrogen atoms and one
    Oxygen atom.
  • Seawater is NOT a substance samples taken at
    different locations will have different
    compositions.

42
Properties of Matter
  • Physical Property can be tested without
    changing the composition of the substance.
  • Water can be frozen but it is still H2O.
  • Ice can be melted but it is still H2O.
  • Water can be boiled to form vapor but it is
    still H2O.

43
Properties of Matter
  • Chemical Property the way a substance combines
    with (reacts with) another substance to form a
    new substance.
  • Sodium an unstable metallic element reacts with
    Chlorine an unstable gaseous element to form
    Sodium Chloride Table Salt.2 Na Cl2 ? 2 NaCl
  • Iron reacts with Oxygen to form rust.4 Fe 3 O2
    ? 2 Fe2O3

44
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45
Properties of Matter
  • States of Matter

46
Properties of Matter
  • States of Matter
  • Solid
  • Liquid
  • Gas

47
Properties of Matter
Solid
  • Has a definite shape and volume
  • Atoms are packed closely together and have an
    orderly arrangement of atoms

48
Properties of Matter
Solid
  • Solids have a definite volume and shape because
    the particles of a solid vibrate around fixed
    locations.

49
Properties of Matter
Solid
  • Solids are only very slightly compressible.

50
Properties of Matter
Liquid
  • Has a definite volume, but not a definite shape
  • Atoms are close together but the arrangement of
    atoms is more random

51
Properties of Matter
Liquid
  • Takes on the shape of its container because
    particles can flow to new locations
  • The volume is constant because forces of
    attraction keep the particles close together.

52
Properties of Matter
Liquid
  • Liquids are slightly compressible.

53
Properties of Matter
Gas
  • Has no definite shape nor definite volume
  • Atoms are loosely spaced and are not arranged in
    a regular pattern

54
Properties of Matter
Gas
  • The constant motion of particles in a gas allows
    a gas to fill a container of any shape or size.

55
Properties of Matter
Gas
  • Gases are highly compressible.

56
Properties of Matter
States of Matter
  • Solid
  • Liquid
  • Gas

57
Properties of Matter
Phase Changes
When enough kinetic energy is added to a solid,
it can become a liquid.
When enough kinetic energy is added to a liquid,
it can become a gas.
58
Properties of Matter
Phase Changes
Melting, freezing, vaporization, condensation,
sublimation and deposition are six common phase
changes.
59
Properties of Matter
Freezing
  • Often, farmers spray water (that freezes) onto
    tender blossoms and fruit to protect them from
    freeze damage.

When water freezes, temperature decreases so
the water is giving up energy.
  • So, freezing is an exothermic change (releases
    heat)!

60
Properties of Matter
Phase Changes
Liquid Gas
Boiling Point
Liquid
Solid / Solid Liquid
Melting Point
Note Temperature does not change during a phase
change.
61
Properties of Matter
  • Endothermic - describes a process or reaction
    that absorbs energy in the form of heat
    Sublimation, melting and vaporization are
    endothermic processes (heat is absorbed).
  • Exothermic - describes a process or reaction that
    releases heat Deposition, freezing and
    condensation are exothermic processes (heat is
    released).

62
Properties of Matter
Chemical Changes
  • Chemical Changes are usually referred to as a
    chemical reaction.
  • Law of Conservation of Mass states that mass is
    neither created nor destroyed during a chemical
    reaction.
  • So, the mass of the reactants must equal the mass
    of the products.

63
Properties of Matter
Mixtures
  • A Mixture is a combination of two or more pure
    substances where each substance keeps its
    individual chemical properties.
  • Heterogeneous Mixture is not blended smoothly
    individual substances remain distinct. Examples
    Sand, Tossed Salad.
  • Homogeneous Mixture SOLUTION there is a
    constant composition throughout. Examples Sugar
    water, Air, Alloy (solution of metals).

64
Properties of Matter
Mixtures Separation Techniques
  • Remember A Mixture is a combination of two or
    more pure substances where each substance keeps
    its individual chemical properties. So, we should
    be able to separate them!

65
Properties of Matter
Mixtures Separation Techniques
  • Methods for Separation
  • Filtration
  • Distillation
  • Crystallization
  • Chromatography

66
Properties of Matter
Mixtures Separation Techniques
  • Filtration a method to separate liquids from
    solids.

67
Properties of Matter
Mixtures Separation Techniques
  • Crystallization a method to recover substances
    in a solution.

68
Properties of Matter
Mixtures Separation Techniques
  • Distillation a method to separate mixtures
    based on boiling points.

69
Properties of Matter
Mixtures Separation Techniques
  • Chromatography a method that separates a
    mixture by its tendency to move across a surface
    of another material.

70
Properties of Matter
Mixtures Separation Techniques
71
Properties of Matter
Elements and Compounds
72
Properties of Matter
Elements and Compounds
73
Properties of Matter
Elements and Compounds
74
Properties of Matter
Elements and Compounds
75
Properties of Matter
Elements and Compounds
76
Properties of Matter
Elements and Compounds
77
Properties of Matter
Elements and Compounds
78
Properties of Matter
Elements and Compounds
79
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80
Elements and Compounds
  • Element a pure substance that cannot be
    separated into simpler sub stances by physical or
    chemical means.
  • Compound a combination of two or more different
    elements that are combined chemically.
  • The properties of a compound are different from
    the properties of the elements it is made of.

81
Elements and Compounds
  • Compounds can be broken down into simpler
    substances by chemical means.Example Water can
    be broken down into Hydrogen and Oxygen2 H2O ?
    2 H2 O2

82
Law of Definite Proportions
Elements and Compounds
  • This law states that regardless of amount, a
    compound is always composed of the same elements
    in the same proportion by mass.
  • When water is broken down, two parts of hydrogen
    and one part of oxygen are always produced. Also,
    the ratio of weight of Oxygen to Hydrogen is
    always 8 1.

83
Law of Multiple Proportions
Elements and Compounds
  • This law states that the same elements can
    combine in different ratios to form different
    compounds.
  • Shown here are two compounds containing Copper
    and Chlorine. Compound 1 is CuCl. Compound 2 is
    CuCl2.

84
Phase Diagrams
85
Phase Diagrams
86
Phase Diagrams
87
SolubilityCurve
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