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CHAPTER 1
Basic Concepts
of Chemistry
Chapter Outline
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1-1
1-2
1-3
1-4
1-5
1-6
1-7
1-8
Chemistry and Its Methods
Sustainability and Green Chemistry
Classifying Matter
Elements
Compounds
Physical Properties
Physical and Chemical Changes
Energy: Some Basic Principles
Chemistry is the study of Matter
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Matter
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Anything that occupies space and has
mass.
Mass
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Measure of the amount of matter that an
object contains.
Chemistry and Its Methods
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Hypothesis: A tentative explanation or prediction
based on experimental observations.
Law: A concise verbal or mathematical statement of a
behavior or a relation that seems always to be the
same under the same conditions.
Theory: a well-tested, unifying principle that explains
a body of facts and the laws based on them. It is
capable of suggesting new hypotheses that can be
tested experimentally.
Qualitative Observations
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No numbers involved
Color, appearance, statements like
“large” or “small
Stating that something is hot or cold
without specifying a temperature.
Identifying something by smell
No measurements
Quantitative Observations
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A quantity or attribute that is
measureable is specified.
Numbers with units are expressed from
measurements.
Dimensions are given such as mass,
time, distance, volume, density,
temperature, color specified as a
wavelength etc...
Goals of Science
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Predict
Control
Understanding
Explaining
Dilemmas and Integrity in Science
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Experimental results should be
reproducible.
Furthermore, these results should be
reported in the scientific literature in
sufficient detail that they can be used or
reproduced by others.
Conclusions should be reasonable and
unbiased.
Credit should be given where it is due.
Sustainability and Green Chemistry
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Prevent waste
Synthetic methods should
maximize materials
Chemical synthesis should
reduce toxicity
Energy requirements should
be minimized
Raw materials should be
renewable and practical
Chemical products should
not persist in the
environment
Substances should be
chosen to minimize risks
Classification of Matter
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Classify according to its physical state
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Gas
Liquid
Solid
Classify according to its composition
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Element
Compound
Mixture
Classifying Matter: State of Matter
States of Matter
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Solid –
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Liquid –
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Definite Shape
Definite Volume
Lowest Kinetic Energy
Indefinite Shape
Definite Volume
Intermediate Kinetic Energy
Gas –
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Indefinite Shape
Indefinite Volume
Highest Kinetic Energy
Classifying Matter
Mixtures: Homogenous and Heterogeneous
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A homogeneous mixture consists of two or
more substances in the same phase. No
amount of optical magnification will reveal a
homogeneous mixture to have different
properties in different regions.
A heterogeneous mixture does not have
uniform composition. Its components are
easily visually distinguishable.
When separated, the components of both
types of mixtures yields pure substances.
Mixtures
Heterogeneous Mixtures can be
separated by filtration.
Mixtures
A combination of two or more pure
substances.
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Homogeneous - Uniform composition
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Heterogeneous - Non-uniform composition
Physical Properties
Mixtures may be separated by physical
properties:
Physical Property
Means of Separation
Density
Decantation,
centrifugation
Boiling point
Distillation
State of Matter
Filtration
Intermolecular Forces
Chromatography
Vapor pressure
Evaporation
Magnetism
Magnets
Solubility
Filtration
Are these heterogeneous or homogenous?
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Blood
Urine
“T-Bone” steak
Gasoline
Twinkie
Colt 45
Pure Substances
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A pure substance has well defined
physical and chemical properties.
Pure substances can be classified as
elements or compounds.
Compounds can be further reduced into
two or more elements.
Elements consist of only one type of
atom. They cannot be decomposed or
further simplified by ordinary means.
Pure Substances
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Element
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Cannot be converted to a simpler form by a
chemical reaction.
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Example: sodium and helium
Compound
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Combination of two or more elements in a definite,
reproducible way.
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Example: water - H2O
Elements
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The elements are recorded on the PERIODIC TABLE.
There are 117 recorded elements at this time.
The Periodic Table will be discussed further in Chapter 2.
Chemical Compounds
Chemical compounds are composed of two or more atom.
Chemical Compounds
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All Compounds are made up of
molecules or ions.
A molecule is the smallest unit of a
compound that retains its chemical
characteristics.
Ionic compounds are described by a
“formula unit”.
Molecules are described by a
“molecular formula”.
Chemical Compounds
Physical Properties
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Characteristics that can be evaluated without
changing the composition of the material
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Color
Odor
Density
Melting point
Thermal conductivity
Volume
Hardness
Physical Properties
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Some physical properties:
− Color
− State (s, g or liq)
− Melting and Boiling
point
− Density (mass/unit
volume)
Extensive properties
(mass) depend upon the
amount of substance.
Intensive properties
(density) do not.
Physical Properties
Physical properties are a function of intermolecular forces.
H
Water (18 g/mol)
liquid at 25oC
Methane (16 g/mol)
gas at 25oC
H
C
H
H
O
H
• Water molecules are attracted to one another by
“hydrogen bonds”. (Chapter 11)
• Methane molecules only exhibit week “London
Forces”. (Chapter 11)
H
Physical Properties
Physical properties
are affected by
temperature
(molecular motion).
The density of water
is seen to change
with temperature.
Chemical Properties
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Results in a change in the composition
of a material.
Explains how one substance acts in the
presence of another.
Chemical Reaction - how the change
occurs.
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A chemical property of wood is
it’s ability to burn - combustion.
Reactants
Products
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Wood + O2
CO2 + water + heat
The reactants and products are very different.
Chemical Properties
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Chemical properties are really chemical changes.
The chemical properties of elements and compounds are
related to periodic trends and molecular structure.
A Scientific Model
Models are commonly used to help visualize
atoms and molecules.
 Atom
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The smallest unit of an element
that has all of the properties of an
element.
Molecule
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The smallest unit of a pure
substance that has all of the
properties of that substance.
It may contain more than one atom and more than one
element.
Molecular Formula
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A molecule is the smallest unit of a
compound that retains the chemical
characteristics of the compound.
Composition of molecules is given by a
molecular formula.
Physical Change
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A change that does not entail any
change in chemical composition
Solid iron (Fe) melting in a blast furnace
Fe(s) → Fe(l)
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Ice cube melting
H2O(s) → H2O(l)
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Chemical Change
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Involves a change in chemical composition
Results in a change in composition or
structure
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Iron metal reacts with oxygen to form rust (iron oxide)
4Fe + 3O2  2 Fe2O3
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H2 and O2 react to form Water
2H2 + O2  2 H2O
Chemical vs. physical change
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Chromatography
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separated components of mixture
didn’t change the components
Electrolysis
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water was changed to hydrogen and
oxygen
Which are chemical or physical changes?
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Mulching leaves
Milk turning sour
Odor of Mothballs
Ice melting
Beer going flat
Energy: Some Basic Principles
Energy can be classified as Kinetic or Potential.
 Kinetic energy is energy associated with motion
such as:
• The motion at the particulate level (thermal
energy).
• The motion of macroscopic objects like a thrown
baseball, falling water.
 The movement of electrons in a conductor (electrical
energy).
 Wave motion, transverse (water) and compression
(acoustic).
Matter consists of atoms and molecules in motion.
Energy: Some Basic Principles
Potential energy results from an object’s
position:
 Gravitational: An object held at a height,
waterfalls, etc.
 Energy stored in an extended spring.
 Energy stored in molecules (chemical energy,
food)
 The energy associated with charged or
partially charged particles (electrostatic
energy)
 Nuclear energy (fission, fusion).