An Introduction to Chemistry
Chapter 1
Hein and Arena
Version 2.0
12th Edition
Eugene Passer
Chemistry Department
Bronx Community College
© John Wiley and Sons, Inc
Chapter Outline
1.1 Why Study Chemistry?
1.2 The Nature of Chemistry
1.6 The Particulate Nature of
Matter
1.3 Thinking Like A Chemist
1.7 The Physical States of Matter
1.4 A Scientific Approach to
Problem Solving
1.8 Classifying Matter
1.5 The Scientific Method
What is a Science?
The observation, identification, description,
experimental investigation, and theoretical
explanation of natural phenomena.
observe
describe
identify
Natural
Phenomena
experimentally
investigate
theoretically
explain
Chemistry
The science of the composition, structure,
properties and reactions of matter, especially
of atomic and molecular systems.
composition
structure
Matter
properties
reactions
1.4
A Scientific Approach to
Problem Solving
Problem Solving
1. Define the problem by recognizing it and
stating it clearly.
In science this is called an observation.
2. Propose solutions to the problem.
In science this is called a hypothesis.
3. Decide the best way to solve the problem.
In science we perform an experiment.
1.5
The Scientific Method
Definitions
• Hypothesis: A
tentative explanation
of certain facts that
provide a basis for
further
experimentation.
• Theory: Wellestablished hypothesis.
An explanation of the
general principles of
certain phenomena
with considerable
evidence or facts to
support it.
Law: Statement of natural phenomena to which no
exceptions are known under the given conditions. A
law is not an explanation.
Outline
Steps
1. Collect facts or data that are relevant to the
problem or question at hand. This is usually
done by experimentation.
2. Analyze the data to find trends (regularities).
3. Formulate a hypothesis that will account for
the data and that can be tested by further
experimentation.
4. Plan and do additional experiments to test the
hypothesis.
5. Modify the hypothesis to ensure
compatibility with the experimental data.
EXPLANATIONS
Hypothesis
Theory
Tentative Explanation
of
Certain Facts
Explanation of the
General Principles
of Certain Phenomena
Provides a
Basis for
Further Experimentation
Considerable Evidence
or Facts
Support It
Law
Simple Statement
of Natural Phenomena
No Exceptions
Under the Given
Conditions
1.6
The Particulate
Nature of Matter
• Matter is anything that has mass
and occupies space.
• Matter can be invisible.
Air is matter, but it cannot be seen.
• Matter appears to be continuous and
unbroken.
─ Matter is actually discontinuous. It is
made up of tiny particles call atoms.
An apparently empty test tube is submerged, mouth
downward in water. Only a small volume of water
rises into the tube, which is actually filled with
invisible matter–air.
1.3
1.7
Physical States
of Matter
SOLIDS
Shape
• Definite - does not change. It is
independent of its container.
Volume
• Definite
Particles
• Particles are close together. They
cling rigidly to each other.
Compressibility • Very slight–less than liquids
and gases.
A solid can be either crystalline or amorphous. Which
one it is depends on the internal arrangement of the
particles that constitute the solid.
Solid
Amorphous Solid
Crystalline Solid
Particles lack a regular
internal arrangement
Particles exist in regular, repeating
three-dimensional geometric patterns.
Glass, plastics, gels
Diamond, metals, salts
LIQUIDS
Shape
• Not definite - assumes the shape of
its container.
Volume
• Definite
Particles
• Particles are close together.
• Particles are held together by strong
attractive forces. They stick firmly
but not rigidly to each other.
• They can move freely throughout
the volume of the liquid.
Compressibility
• Very slight–greater than solids,
less than gases.
GASES
Shape
• No fixed shape.
Volume
• Indefinite.
Particles
• Particles are far apart compared to
liquids and solids.
• Particles move independently of
each other.
GASES
Compressibility
• The actual volume of the gas
particles is small compared to
the volume of space occupied
by the gas.
– Because of this a gas can be
compressed into a very small
volume or expanded almost
indefinitely.
ATTRACTIVE FORCES
Solid
• Attractive forces are strongest in a
solid.
– These give a solid rigidity.
Liquid
• Attractive forces are weaker in
liquids than in solids.
– They are sufficiently strong so that a
liquid has a definite volume.
ATTRACTIVE FORCES
Gas
• Attractive forces in a gas are
extremely weak.
• Particles in the gaseous state have
enough energy to overcome the
weak attractive forces that hold
them together in liquids or solids.
– Because of this the gas particles move
almost independently of each other.
1.8
Classifying Matter
Matter refers to all of the materials that
make up the universe.
Substance
A particular kind of matter that has a fixed
composition and distinct properties.
Examples
ammonia, water, and oxygen.
Homogeneous Matter
Matter that is uniform in appearance
and with uniform properties throughout.
Examples
ice, soda, pure gold
Heterogeneous Matter
Matter with two or more physically
distinct phases present.
Examples
ice and water, wood, blood
Homogeneous
Heterogeneous
Phase
A homogenous part of a system separated
from other parts by physical boundaries.
Examples
In an ice water mixture, ice is the solid
phase and water is the liquid phase.
Mixture
Matter containing 2 or more substances that
are present in variable amounts. Mixtures
are variable in composition. They can be
homogeneous or heterogeneous.
Homogeneous Mixture (Solution)
A homogeneous mixture of 2 or more
substances. It has one phase.
Example
Sugar and water. Before the sugar and
water are mixed, each is a separate phase.
After mixing the sugar is evenly dispersed
throughout the volume of the water.
Heterogeneous Mixture
A heterogeneous mixture consists of 2 or
more phases.
Example
Sugar and fine white sand. The amount of
sugar relative to sand can be varied. The
sugar and sand each retain their own
properties.
Heterogeneous Mixture
A heterogeneous mixture consists of 2 or more
phases.
Example
• Iron (II) sulfide (FeS) is 63.5% Fe and 36.5% S
by mass.
• Mixing iron and sulfur in these proportions does
not form iron (II) sulfide. Two phases are
present: a sulfur phase and an iron phase.
• If the mixture is heated strongly a chemical
reaction occurs and iron (II) sulfide is formed.
• FeS is a compound of iron and sulfur and has
none of the properties of iron or sulfur.
Heterogeneous Mixture
solid phase1
liquid phase
solid phase2
Mixture of iron
and sulfur
Compound of iron
and sulfur
Formula
Has no definite
formula: consists
of Fe and S.
FeS
Composition
Contains Fe and S
in any proportion
by mass.
63.5% Fe and
36.5% S by mass.
Separation
Fe and S can be
separated by
physical means.
Fe and S can be
separated only by
chemical change.
Heterogeneous Mixture
of One Substance
A pure substance can exist as different
phases in a heterogeneous system.
Example
Ice floating in water consists of two
phases and one substance. Ice is one
phase, and water is the other phase. The
substance in both cases is the same.
System
The body of matter under consideration.
Examples
In an ice water mixture, ice is the solid
phase and water is the liquid phase. The
system is the ice and water together.
Classification of matter: A pure substance is always
homogeneous in composition, whereas a mixture
always contains two or more substances and may
be either homogeneous or
heterogeneous.
1.6