Chapter 1
“Introduction to
Chemistry”
Chapter 2
“Matter & Change”
1
What is Chemistry?
 Chemistry
is the study of the
composition of “matter” – (matter is
anything with mass and occupies
space), its composition, properties, and
the changes it undergoes.
 Has a definite affect on everyday life taste of foods, grades of gasoline, etc.
 Living and nonliving things are made of
matter.
2
Chemistry is the
study of the
composition,
structure, and
properties of matter
and the changes it
undergoes – such
as burning fuels.
C2H5OH + 3 O2  2 CO2 + 3 H2O + Energy
Reactants
3

Products
5 Major Areas of Chemistry
Analytical Chemistry- concerned with
the composition of substances.
2) Inorganic Chemistry- primarily deals
with substances without carbon
3) Organic Chemistry- essentially all
substances containing carbon
4) Biochemistry- Chemistry of living things
5) Physical Chemistry- describes the
behavior of chemicals (ex. stretching);
involves lots of math!
Boundaries not firm – they overlap and interact
1)
4
What is Chemistry?
 Pure
chemistry- gathers knowledge for
the sake of knowledge
 Applied Chemistry- is using chemistry
to attain certain goals, in fields like
medicine, agriculture, and
manufacturing – leads to an application
* Aspirin (C9H8O4) - to relieve pain
* Use of TECHNOLOGY (benefit!)
5
Why Study Chemistry?
 Everyone
and everything around us
involves chemistry – explains our world
 What in the world isn’t Chemistry?
 Helps you make choices; helps make
you a better informed citizen
 A possible career for your future
 Used to attain a specific goal
6
Why Study Chemistry?
•Major component of acid rain
•May cause burns
•Has been found in tumors
•Used in nuclear plants
•Used in the distribution of
pesticides
•Used in animal research
7
Chemistry Far and Wide
 Chemists
design materials to fit
specific needs – velcro (Patented in 1955)
 perfume, steel, ceramics, plastics,
rubber, paints, nonstick cooking
utensils, polyester fibers
 Two different ways to look at the
world: macroscopic and
microscopic
8
Chemistry Far and Wide
– we constantly have
greater demands
–We can conserve it; use wisely
–We can try to produce more; oil
from soybeans to make biodiesel
–fossil fuels, solar, batteries (that
store energy – rechargeable?),
nuclear (don’t forget pollution!)
 Energy
9
Chemistry Far and Wide
 Medicine
and Biotechnology–Supply materials doctors use to
treat patients
–vitamin C, penicillin, aspirin (C H O )
–materials for artery transplants
and hipbones
–bacteria producing insulin
9
10
8
4
Chemistry Far and Wide
 Agriculture
–Produce the world’s food supply
–Use chemistry for better
productivity – soil, water, weeds
–plant growth hormones
–ways to protect crops; insecticides
–disease resistant plants
11
Chemistry Far and Wide
 The
Environment
–both risks and benefits involved in
discoveries
–Pollutants need to be 1) identified
and 2) prevented
–Lead paint was prohibited in 1978;
Leaded gasoline? Drinking water?
–carbon dioxide, ozone, global
warming
12
Chemistry Far and Wide
 The
Universe
–Need to gather data from afar,
and analyze matter brought back
to Earth
–composition of the planets
–analyze moon rocks (or Mars)
–planet atmospheres
–life on other planets?
13
Alchemy – developed the tools and
techniques for working with chemicals
 The word chemistry comes from
alchemy – practiced in China and
India since 400 B.C.
 Alchemy has two sides:
–Practical: techniques for working
with metals, glass, dyes, etc.
–Mystical: concepts like perfection –
gold was a perfect metal
14
An Experimental Approach
 In
the 1500s, a shift started from
alchemy to science – King Charles
II was a supporter of the sciences
 “Royal Society of London for the
Promotion of Natural Knowledge”
 Encouraged scientists to use more
experimental evidence, and not
philosophical debates
15
Lavoisier
 In
the late 1700s, Antoine
Lavoisier helped transform
chemistry from a science of
observation to the science of
measurement – still used today
 He settled a long-standing debate
about burning, which was…
–Oxygen was required!
16
The Scientific Method
A
logical approach to solving
problems or answering questions.
 Starts with observation- noting and
recording information and facts
 hypothesis- a proposed
explanation for the observation;
must be tested by an experiment
17
Steps in the Scientific Method
1. Observations (uses your senses)
a) quantitative involves numbers = 95oF
b) qualitative is word description = hot
2. Formulating hypotheses (ideas)
- possible explanation for the
observation, or “educated” guess
3. Performing experiments (the test)
- gathers new information to help decide
whether the hypothesis is valid
18
Scientific Method




19
“controlled” experiment- designed to
test the hypothesis
only two possible answers:
1) hypothesis is right (supported)
2) hypothesis is wrong (not supported)
We gather data and observations by
doing the experiment
Modify hypothesis - repeat the cycle
Scientific Method
We deal with variables, or factors that can
change. Two types:
1) Manipulated variable (or independent
variable) is the one that we change
2) Responding variable (or dependent
variable) is the one observed during the
experiment
 For results to be accepted, the experiment
needs to always produce the same result

20
Outcomes over the long term…
21

Theory (Model)
- A set of well-tested hypotheses that give
an overall explanation of some natural
phenomenon – not able to be proved

Natural Law (or Scientific Law)
- The same observation applies to many
different systems; summarizes results
- an example would be:
the Law of Conservation of Mass
Law vs. Theory
A law
summarizes what has
happened.
A theory (model) is an
attempt to explain why it
happened – this changes as
new information is gathered.
22
Collaboration / Communication
 When
scientists share ideas by
collaboration and communication,
they increase the likelihood of a
successful outcome
 Collaboration
 How is communication done?
 Is the Internet reliable information?
23
Luis Alvarez Story
•Iridium (30 – 130 times) normal
•It’s very rare???
•This layer is found around the planet
24
Luis Alvarez Story
???
25
Luis Alvarez Story
X
26
Problem Solving in Chemistry
 We
are faced with problems each
day, and not just in chemistry
 A solution (answer) needs to be found
 Trial and Error may work sometimes?
there is a method to problem
solving that works better, and these
are skills that no one is born knowing
– they need to be learned.
 But,
27
Problem Solving in Chemistry


28
Effective problem solving usually
involves two general steps:
1) Developing a plan
2) Implementing that plan
The skills you use to solve a word
problem in chemistry are NOT
different from those techniques
used in shopping, cooking, or
planning a party.
Solving Numeric Problems
 Measurements
are an important part
of chemistry; thus many of our word
problems involve use of mathmatics
–Word problems are real life
problems, and sometimes more
information is presented than
needed for a solution
 Following skills presented will help
you become more successful
29
Solving Numeric Problems

The three steps we will use for
solving a numeric word problem are:
1) Analyze
2) Calculate
3) Evaluate

30
Let’s learn how
to ACE these
numeric word
problems!
The following slides tell the meaning
of these three steps in detail.
Solving Numeric Problems
1) Analyze: this is the starting point

31
– Determine what are the known factors,
and write them down on your paper!
– Determine what is the unknown. If it is
a number, determine the units needed
– Plan how to relate these factorschoose an equation; use table or graph
This is the heart of successful problem
solving techniques – it is the PLAN
Solving Numeric Problems
2) Calculate: perform the mathematics
– If your plan is correct, this is the
easiest step.
– Calculator used? Do it correctly!
– May involve rearranging an
equation algebraically; or, doing
some conversion of units to some
other units.
32
Solving Numeric Problems
3) Evaluate: – the finishing step
– Is it reasonable? Make sense?
Do an estimate for the answer,
and check your calculations.
– Need to round off the answer?
– Do you need scientific notation?
– Do you have the correct units?
– Did you answer the question?
33
Solving Conceptual Problems




34
Not all word problems in chemistry
involve doing calculations
Nonnumeric problems are called
conceptual problems – ask you to apply
concepts to a new situation
Steps are:
1) Analyze and 2) Solve
Plan needed to link known to unknown,
but no checking units or calculations
Matter
 Matter
is anything that: a) has
mass, and b) takes up space
 Mass = a measure of the amount
of “stuff” (or material) the object
contains (don’t confuse this with
weight, a measure of gravity)
 Volume = a measure of the space
occupied by the object
35
Describing Matter

Properties used to describe matter
can be classified as:
1) Extensive – depends on the
amount of matter in the sample
- Mass, volume, calories are examples
2) Intensive – depends on the type
of matter, not the amount present
- Hardness, Density, Boiling Point
36
Properties are…
 Words
that describe matter (adjectives)
 Physical Properties- a property that can
be observed and measured without
changing the material’s composition.
 Examples- color, hardness, m.p., b.p.
 Chemical Properties- a property that
can only be observed by changing the
composition of the material.
 Examples- ability to burn, decompose,
ferment, react with, etc.
37
States of matter
1) Solid- matter that can not flow (definite
shape) and has definite volume.
2) Liquid- definite volume but takes the
shape of its container (flows).
3) Gas- a substance without definite volume
or shape and can flow.
– Vapor- a substance that is currently a
gas, but normally is a liquid or solid at
room temperature. (Which is correct:
“water gas”, or “water vapor”?)
38
States of Matter
Definite Definite
Volume? Shape?
Solid
Liquid
Gas
39
YES
YES
NO
Result of a
TemperatureI Will it
Compress?
ncrease?
YES
Small
Expans.
NO
NO
Small
Expans.
NO
NO
Large
Expans.
YES
4th state: Plasma - formed at
high temperatures; ionized phase
of matter as found in the sun
40
Three Main Phases
41
Condense
Freeze
Evaporate
Melt
Solid
42
Liquid
Gas
Copper Phases - Solid
43
Copper Phases - Liquid
44
Copper Phases – Vapor (gas)
45
Physical vs. Chemical Change
 Physical
change will change the visible
appearance, without changing the
composition of the material.
– Boil, melt, cut, bend, split, crack
– Is boiled water still water?
 Can be reversible, or irreversible
 Chemical change - a change where a
new form of matter is formed.
– Rust, burn, decompose, ferment
46
Mixtures are a physical blend of at
least two substances; have variable
composition. They can be either:
1) Heterogeneous – the mixture is not
uniform in composition
• Chocolate chip cookie, gravel, soil.
2) Homogeneous - same composition
throughout; called “solutions”
• Kool-aid, air, salt water
 Every part keeps it’s own properties.

47
Solutions are homogeneous mixtures
 Mixed
molecule by molecule, thus too
small to see the different parts
 Can occur between any state of
matter: gas in gas; liquid in gas; gas
in liquid; solid in liquid; solid in solid
(alloys), etc.
 Thus, based on the distribution of
their components, mixtures are called
homogeneous or heterogeneous.
48
Phase?
 The
term “phase” is used to describe
any part of a sample with uniform
composition of properties.
 A homogeneous mixture consists of a
single phase
 A heterogeneous mixture consists of
two or more phases.
49
Separating Mixtures
 Some
can be separated easily by
physical means: rocks and marbles,
iron filings and sulfur (use magnet)
 Differences in physical properties
can be used to separate mixtures.
 Filtration - separates a solid from
the liquid in a heterogeneous
mixture (by size) – Figure 2.7, page 46
50
Separation of a Mixture
Components of dyes such as ink may be
separated by paper chromatography.
51
Separation of a Mixture
Distillation: takes advantage
of different boiling points.
NaCl boils at 1415 oC
52
Substances are
either:
a) elements, or
b) compounds
53
Substances: element or compound


54
Elements- simplest kind of matter
– cannot be broken down any simpler and
still have properties of that element!
– all one kind of atom.
Compounds are substances that can be
broken down only by chemical methods
– when broken down, the pieces have
completely different properties than the
original compound.
– made of two or more atoms, chemically
combined (not just a physical blend!)
Compound vs. Mixture
Compound
55
Mixture
Made of one kind
of material
Made of more than
one kind of material
Made by a
chemical change
Made by a
physical change
Definite
composition
Variable
composition
Which is it?
Mixture
Element
Compound
56
Elements vs. Compounds
 Compounds can be broken down
into simpler substances by
chemical means, but elements
cannot.
 A “chemical change” is a change
that produces matter with a
different composition than the
original matter.
57
Chemical Change
A change in which one or more
substances are converted into different
substances.
Heat and
light are
often
evidence of
a chemical
change.
58
Properties of Compounds
 Quite
different properties than their
component elements.
 Due to a CHEMICAL CHANGE, the
resulting compound has new and
different properties:
• Table sugar – carbon, hydrogen,
oxygen
• Sodium chloride – sodium, chlorine
• Water – hydrogen, oxygen
59
Classification of Matter
60
Symbols & Formulas
Currently, there are ”117” elements
 Elements have a 1 or two letter symbol,
and compounds have a formula.
 An element’s first letter always capitalized;
if there is a second letter, it is written
lowercase: B, Ba, C, Ca, H, He

 You
Must Learn the elements names
and symbols
61
Chemical Changes
 The
ability of a substance to undergo
a specific chemical change is called a
chemical property.
• iron plus oxygen forms rust, so the
ability to rust is a chemical property
of iron
 During a chemical change (also called
chemical reaction), the composition of
matter always changes.
62
Chemical Reactions are…
 When
one or more substances are
changed into new substances.
 Reactants- the stuff you start with
 Products- what you make
 The products will have NEW PROPERTIES
different from the reactants you started
with
 Arrow points from the reactants to the
new products
63
Recognizing Chemical Changes
1) Energy is absorbed or released
(temperature changes hotter or colder)
2) Color changes (watch out for dilution)
3) Gas production (bubbling, fizzing, or odor
change; smoke)
4) formation of a precipitate - a solid that
separates from solution (won’t dissolve)
64
Conservation of Mass
 During
any chemical reaction, the
mass of the products is always equal
to the mass of the reactants.
 All the mass can be accounted for:
–Burning of wood results in products
that appear to have less mass as
ashes; where is the rest?
Law
65
of conservation of mass
- Page 55
43.43 g Original mass = 43.43 g Final mass
reactants
66
=
product