2009, Prentice-Hall, Inc.. HAVE YOU EVER WONDERED Why the stars shine? Why ice melts and water...
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Transcript of 2009, Prentice-Hall, Inc.. HAVE YOU EVER WONDERED Why the stars shine? Why ice melts and water...
HAVE YOU EVER WONDERED
Why the stars shine?
Why ice melts and water evaporates?
Why do leaves turn colors in the fall, and
how does a battery generate electricity?
Why does keeping foods cold slow their
spoilage, and how do our bodies use food to
maintain life?
Chemistry is the study of matters and the changes it undergoes.
How do chemical principles operate in all aspects of our lives?
CHEMISTRY
IS…
Chemistry is the study of the properties and behavior of matter.
Matter: the physical material of the universe;
anything that has mass and occupies space Property: any characteristic that allows us to
recognize a particular type of matter and to distinguish it from other types
Elements: basic substances that comprise matters Atoms: infinitesimally small building blocks of matter Molecules: matters in which two or more atoms are
joined together in specific shapes
1.1 THE STUDY OF CHEMISTRYTHE ATOMIC AND MOLECULAR PERSPECTIVE OF
CHEMISTRY
1.1 THE STUDY OF CHEMISTRYTHE ATOMIC AND MOLECULAR PERSPECTIVE OF
CHEMISTRY
To satisfy our curiosity?
Because it is an essential part of your curriculum?
To understand our world and how it works
1.1 THE STUDY OF CHEMISTRY
WHY STUDY CHEMISTRY?
FIGURE 1.2 Chemistry helps us understand the world around us.
To improve health care
To provide our everyday
needs for food, clothing,
and shelter
Chemistry helps us better
understand materials
The central science
1.1 THE STUDY OF CHEMISTRY
WHY STUDY CHEMISTRY?
Worldwide sales of chemical products: $550 billion/yr (U.S.)
Chemical industry employs >10% of all scientists/engineers
no fixed volumeno shape
fixed volumeno shape
fixed volumeand shape
1.2 CLASSIFICATIONS OF MATTER
STATES OF MATTER
Matter that has distinct properties and a composition
that does not vary from sample to sample.
(water & NaCl)
Element, compound, and mixture
1.2 CLASSIFICATIONS OF MATTER
PURE SUBSTANCES
Only one kind of atom is in any element Compounds must have at least two kinds of atoms
Pure chemical substances consisting of one type
of atom
118 elements are known (March 2010)
1.2 CLASSIFICATIONS OF MATTER
ELEMENTS
Pure chemical substances consisting of
two or more elements:
contain two or more kinds
of atoms
1.2 CLASSIFICATIONS OF MATTER
COMPOUNDS
1.2 CLASSIFICATIONS OF MATTERCOMPOUNDS
The properties of water bear no resemblance to the properties of its component elements
Heterogeneous mixtures do not have the same composition, properties, and appearance throughout
Homogeneous mixtures have the same composition, properties, and appearance throughout (solutions)
1.2 CLASSIFICATIONS OF MATTER
MIXTURES
Copper sulfateRock
1.2 CLASSIFICATIONS OF MATTER
Sample Exercise 1.1 Distinguishing among Elements, Compounds, and Mixtures
homogeneous mixture.
Solution
“White gold” contains gold and a “white” metal, such as palladium. Two samples of white gold differ in the relative amounts of gold and palladium they contain. Both samples are uniform in composition throughout. Use Figure 1.9 to classify white gold.
Aspirin is composed of 60.0% carbon, 4.5% hydrogen, and 35.5% oxygen by mass, regardless of its source. Use Figure 1.9 to classify aspirin.
Practice Exercise
Answer: compound
Physical Properties…
• Can be observed without changing a substance into another
substance.
• Boiling point, density, mass, volume, etc.
Chemical Properties…
• Can only be observed when a substance is changed into
another substance.
• Flammability, corrosiveness, reactivity with acid, etc.
1.3 PROPERTIES OF MATTER
TYPES OF PROPERTIES
Intensive Properties…
• Are independent of the amount of the substance that is
present.
• Temperature, density, boiling point, color, etc.
Extensive Properties…
• Depend upon the amount of the substance present.
• Mass, volume, etc.
1.3 PROPERTIES OF MATTER
TYPES OF PROPERTIES
Physical Changes
• These are changes in matter that do not change the
composition of a substance.
• Changes of state, temperature, volume, etc.
Chemical Changes
• Chemical changes result in new substances.
• Combustion, oxidation, decomposition, etc.
1.3 PROPERTIES OF MATTER
TYPES OF PROPERTIES
1.3 PROPERTIES OF MATTERPHYSICAL AND CHEMICAL CHANGES
FIGURE 1.10 A chemical reaction
1.3 PROPERTIES OF MATTERPHYSICAL AND CHEMICAL CHANGES
FIGURE 1.11 The chemical reaction between a copper penny and nitric acid
In filtration, solid substances are separated from
liquids and solutions.
Salt / copper
1.3 PROPERTIES OF MATTERSEPARATION OF MIXTURES
FIGURE 1.12 Separation by filtration
Distillation uses differences in the boiling points of
substances to separate a homogeneous mixture into
its components.
1.3 PROPERTIES OF MATTERSEPARATION OF MIXTURES
FIGURE 1.13 Distillation
• The differing abilities of substances to interact with the surfaces of various solids such as paper and starch can be used to separate mixtures.
Chromatography
1.3 PROPERTIES OF MATTERSEPARATION OF MIXTURES
FIGURE 1.14 Separation of ink into components
The metric system
• An international system
of measurement, first
adopted by France in
1791, that is the
common system of
measuring units used by
most of the world.
1.4 UNITS OF MEASUREMENTTHE METRIC SYSTEM AND SI UNITS
FIGURE 1.15 Metric units. Fluid ounces (fl oz), English units; mL, metric units
1.4 UNITS OF MEASUREMENTSI UNITS
The world's most widely used system of
measurement, both in everyday commerce and in
science.
From seven base units, all other units are derived
1.4 UNITS OF MEASUREMENTSI UNITS
Length and mass
• The SI base units of length and mass are the
meter (m) and kilogram (kg).
Temperature
• A measure of the hotness or coldness of an object.
• The Celsius (˚C) scale: the freezing point (0 ˚C) and
boiling point (100 ˚C) of water.
• The Kelvin (K) scale: The SI unit of temperature.
1.4 UNITS OF MEASUREMENTSI UNITS
• The Kelvin (K) scale- The temperature at which all thermal motion ceases in the
classical description of thermodynamics is defined as 0 K.
- The reference point that defines the Kelvin scale is the triple
point of water at 273.16K (0.01 ˚C).
Temperature
1.4 UNITS OF MEASUREMENTSI UNITS
Temperature
1.4 UNITS OF MEASUREMENTSI UNITS
Volume
1.4 UNITS OF MEASUREMENTDERIVED UNITS
Density is defined as
the amount of mass in
a unit volume of a
substance. ( g/cm or g/mL)
1.4 UNITS OF MEASUREMENTDERIVED UNITS
Exact numbers• 12 eggs in a dozen
• 1000 g in a kilogram
• 1 kg = 2.2046 lb
Inexact numbers• Numbers obtained by measurement
• Uncertainties always exist in measured quantities.
1.5 UNCERTAINTY IN MEASUREMENTEXACT NUMBERS AND INEXACT
NUMBERS
precision• a measure of how closely individual
measurements agree with one another.
• standard deviation, reproducibility
accuracy• a measure of how closely individual
measurements agree with the correct, or true
value
1.5 UNCERTAINTY IN MEASUREMENT
PRECISION AND ACCURACY
All digits of a measured quantity, including the
uncertain one, are called significant figures.
1.5 UNCERTAINTY IN MEASUREMENT
SIGNIFICANT FIGURES
FIGURE 1.24 uncertainty and significant figures in a measurement
1.5 UNCERTAINTY IN MEASUREMENT
SIGNIFICANT FIGURES
All nonzero digits are significant. Zeros between two significant figures are
themselves significant. (1005 kg, 1.03 cm) Zeros at the beginning of a number are never
significant. (0.02 g, 0.00025 cm) Zeros at the end of a number are significant if a
decimal point is written in the number. (0.0200 g, 3.0 cm)
10,300 g•1.03 × 104 g•1.030 × 104 g•1.0300 × 104 g
1.5 UNCERTAINTY IN MEASUREMENT
SIGNIFICANT FIGURES
1.5 UNCERTAINTY IN MEASUREMENT
SIGNIFICANT FIGURES
Addition and subtraction
Multiplication and division
In rounding off numbers•7.248 → 7.2•2.376 → 2.4•4.735 → 4.74
1.5 UNCERTAINTY IN MEASUREMENT
SIGNIFICANT FIGURES IN CALCULATIONS
1.5 UNCERTAINTY IN MEASUREMENT
SIGNIFICANT FIGURESSample Exercise 1.7 Determining the Number of Significant Figures
in a Calculated Quantity
The width, length, and height of a small box are 15.5 cm, 27.3 cm, and 5.4 cm, respectively. Calculate the volume of the box, using the correct number of significant figures in your answer.
It takes 10.5 s for a sprinter to run 100.00 m. Calculate her average speed in meters per second, and express the result to the correct number of significant figures.
Answer: 9.52 m/s (three significant figures)
Practice Exercise