Introduction
to
1 AnAn
Introduction
to Chemistry
Chemistry
The vibrant colors of the aurora borealis are
the result of chemistry in our atmosphere.
Foundations of College Chemistry, 14th Ed.
Morris Hein and Susan Arena
Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
Chapter Outline
1.1
The Nature of Chemistry
A. Thinking Like a Chemist
1.2
A Scientific Approach to Problem Solving
A. The Scientific Method
1.3
The Particulate Nature of Matter
A. Physical States of Matter
1.4
Classifying Matter
A. Distinguishing Mixtures from Pure Substances
© 2014 John Wiley & Sons, Inc. All rights reserved.
The Nature of Chemistry
Chemistry is the science of matter.
Matter is any object that has mass and occupies space.
Chemistry deals with the composition, structure,
properties, reactions and energetics of matter.
Chemists devise experiments, interpret data
and synthesize new substances.
© 2014 John Wiley & Sons, Inc. All rights reserved.
Thinking Like a Chemist
Chemists try to understand how and why chemical
changes occur in nature and the human body.
Chemists try to explain the macroscopic world,
which is observable to the eye…
…and the microscopic world, which is made up of objects
too small to see, like atoms and molecules.
© 2014 John Wiley & Sons, Inc. All rights reserved.
A Microscopic View of Water
Imagine holding one molecule of water in your hand.
What does it look like?
Water (H2O) is composed of two hydrogen atoms
and one oxygen atom.
The atoms must connect in a specific arrangement,
in this case forming two O-H bonds.
© 2014 John Wiley & Sons, Inc. All rights reserved.
A Scientific Approach to Problem Solving
Scientists use a logical process to explain
the world around them.
This process is called the Scientific Method.
© 2014 John Wiley & Sons, Inc. All rights reserved.
The Scientific Method
The Scientific Method
1. Collect the facts and data relevant to your question.
Perform an experiment, then analyze the resulting
data to look for trends that relate to the question.
2. Formulate a hypothesis.
A hypothesis is a tentative explanation of the data
that requires further experimentation to be validated.
3. Plan and perform additional experiments to test the
hypothesis.
4. Modify the hypothesis.
A useful hypothesis must explain all of the data.
© 2014 John Wiley & Sons, Inc. All rights reserved.
The Scientific Method
A well-established hypothesis is often called a theory.
A theory summarizes a hypothesis that has been
supported by repeated experimentation. A theory
is valid as long as there is no evidence to disprove it.
A scientific law is a statement of natural phenomenon
where no exceptions are known under the given conditions.
© 2014 John Wiley & Sons, Inc. All rights reserved.
The Particulate Nature of Matter
Matter appears in many forms, both big and small.
On the microscopic level, all matter is composed of
discrete, tiny fundamental particles called atoms.
Using a scanning tunneling microscope, individual atoms
can be configured into specific arrangements.
© 2014 John Wiley & Sons, Inc. All rights reserved.
Physical States of Matter
Matter exists as three physical states: solid, liquid and gas.
A solid has definite shape and volume which
can be independent of its container.
The most common solids are crystalline and have regular,
repeating three-dimensional geometric patterns.
Solid water
molecules are
held together
rigidly and are
very close to each
other.
© 2014 John Wiley & Sons, Inc. All rights reserved.
Physical States of Matter
Some solids such as plastics, glass and gels do not have
regular, internal geometric patterns.
These solids are called amorphous solids,
meaning without shape or form.
© 2014 John Wiley & Sons, Inc. All rights reserved.
Physical States of Matter
A liquid has definite volume but not a definite shape.
Liquid particles are held together by strong attractive
forces and are able to move freely.
Liquids are fluid which allows them to take
the shape of the container.
Liquid water molecules
are close together but
are free to move around
and slide over each other.
© 2014 John Wiley & Sons, Inc. All rights reserved.
Physical States of Matter
A gas has indefinite volume and no fixed shape.
Gas particles move independently and are relatively far
apart, which allows them to completely fill a container.
Gases can be compressed or expanded almost indefinitely.
Gaseous water molecules are
far apart and move freely and
randomly.
© 2014 John Wiley & Sons, Inc. All rights reserved.
Physical States of Matter
Although matter is separated into discrete units,
attractive forces hold the particles together and
give matter its appearance of continuity.
Attractive forces are strongest in solids, giving them
rigidity; weaker in liquids but strong enough to
maintain definite volumes; and weakest in gases
which allows them to behave nearly independently.
© 2014 John Wiley & Sons, Inc. All rights reserved.
Classifying Matter
Matter can be subdivided into specific categories.
A pure substance has a definite, fixed composition
and is either an element or a compound.
The sugar on the spoon and the
water in the beaker are
each a pure substance –
both are compounds.
© 2014 John Wiley & Sons, Inc. All rights reserved.
Classifying Matter
Homogeneous matter is uniform in appearance and
has the same properties throughout.
Heterogeneous matter consists of two or more
physically distinct phases.
A phase is a homogeneous part of a system separated
from other parts by a physical boundary.
Ice floating in water is a two phase system.
Each phase is homogeneous but the overall system
is heterogeneous.
© 2014 John Wiley & Sons, Inc. All rights reserved.
Mixtures
A mixture is a combination of two or more
pure substances and can be homo- or heterogeneous.
Sugar dissolved in water is a homogeneous mixture.
The proportion of sugar and water can be varied
but the composition will be the same throughout.
© 2014 John Wiley & Sons, Inc. All rights reserved.
Mixtures
A heterogeneous mixture will have a different
composition depending on where the sample is taken.
Oil and water form a heterogeneous mixture.
The oil layer floats on top of the water layer.
A sample taken from the top of the mixture will have a
different composition from a sample taken on the bottom.
© 2014 John Wiley & Sons, Inc. All rights reserved.
Separation of Mixtures
The components of a mixture do not lose their identities
and may be separated by physical means such as:
boiling, filtration, floatation, magnetism
Sulfur and iron can be separated using a magnet.
© 2014 John Wiley & Sons, Inc. All rights reserved.
Let’s Practice!
a.
b.
c.
d.
e.
Which of the following is a heterogeneous mixture?
baking soda
gasoline
grape juice
copper metal
soil
© 2014 John Wiley & Sons, Inc. All rights reserved.
Let’s Practice!
Which of the following is a homogeneous mixture?
a. carbon dioxide
b. mercury
c. maple syrup
d. concrete
e. italian salad dressing
Filtration is a common method to separate components
of what type of mixture?
a.
b.
c.
d.
homogeneous mixture of 2 liquids
heterogeneous mixture of 2 liquids
heterogeneous mixture of solid in liquid
homogeneous mixture of solid in liquid
© 2014 John Wiley & Sons, Inc. All rights reserved.