Transcript Chapter 1 Chemistry: The Science of Matter

Chapter 1
Chemistry: The
Science of Matter
Section 1.1: The Puzzle of Matter
Section 1.2: Properties and Changes of
Matter
Section 1.1 Objectives
Classify matter according to its
composition.
 Distinguish among elements, compounds,
homogeneous mixtures, and
heterogeneous mixtures.
 Relate the properties of matter to its
structure.

Composition, Structure and
Behavior
Chemistry- the science that investigates
and explains the structure and properties
of matter.
 Matter- anything that takes up space and
has mass
 Mass- the measure of the amount of
matter that an object contains
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Matter
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Matter is all around you.
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Phone
Your neighbor
The desk
The metal of your chair
The air you are breathing
What isn’t matter
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Heat
Light
Thoughts
Ideas
Radio waves
 Magnetic fields
Mass
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On earth we equate mass with weight.
A
bowling ball has a larger mass than a tennis
ball.
 I have more mass than the text book.
Matter
The structure of matter refers to its
composition-what is it made of and how is
it organized
 The properties of matter describe the
characteristics and behavior of matter.
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 Changes
matter undergoes
Comparing Composition and
Behavior (Figure 1.2 page 5)
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Salt and Water
 Salt
is Na and Cl
 Water is H and O
 You can wash you hair in water, but not in salt. And
you sprinkle water over popcorn.
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Aspirin and Sucrose
 Both
are composed of C, H, and O
 You wouldn’t use aspirin to sweeten cereal or use
sucrose for a headache
Properties

You can determine some of the properties
of a particular chunk of matter by
examination and manipulation.
 What
is its color?
 Is it a solid, liquid or gas?
 Is it soft or hard?
 Does it dissolve in water?
Properties of Iron
Strong, but can be flattened and stretched
 Does not dissolve in water
 Turns to a liquid at high temperatures
 Is a gray, shiny solid
 Is attracted to a magnet
 Conduct electricity

Properties and Composition
You may be able to determine many
properties of a piece of matter by
examining it and doing some simple tests.
 However, you can not determine what it is
composed of just by looking at it.
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Examining Matter: The
Macroscopic View of Matter
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The macroscopic view of matter is one in
which you touch, smell, taste and see.
The Submicroscopic View of Matter
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Gives you a glimpse into the world of atoms
You cannot see this world even with the most powerful
microscopic.
Matter is made up of atoms
Atoms are so small that a period at the end of a
sentence is made up of 100,000,000,000,000,000,000
(100 quintillion) carbon atoms.
If you could count all 100 quintillion atoms at a rate of
three per second it would take you a trillion years to
finish counting.
Macro, micro, submicro
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Macroscopic – I can see with my “naked” eye
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Microscopic – I need a microscope to see
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Submicroscopic – I can’t see even with the most
powerful microscope
Scanning Tunneling Microscope
(STM)
Although you cannot see atoms the STM
can produce images on a computer screen
that show the location of individual atoms.
 Platinum

Using Models in Chemistry
In chemistry you will use macroscopic and
sub-microscopic models to understand
certain concepts.
 Scientific model- a thinking device, built on
experimentation, that helps us to
understand and explain macroscopic
observations.
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Models
A model for the atom was discussed in
Greece about 2,500 years ago. However,
this was not a scientific model.
 The scientific model of the atom was not
proposed until the 1800’s and it has with
stood much experimentation with little
changes.
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Classifying Matter
Matter can be classified by its composition
 There are two main types of classifications
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 Qualitative-
an observation made without
measurement.
 Quantitative- an observation made with
measurement
Qualitative vs. Quantitative
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Qualitative
 There
are students in this room
 Sucrose contains carbon, oxygen and
hydrogen
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Quantitative
 There
are 24 students in this room
 Sucrose contains 42.1 g of carbon, 51.4 g of
oxygen and 6.5 g of hydrogen.
Pure vs. Mixture
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Matter can be classified by its purity.
Is the matter pure or is it a mixture?
Pure in chemistry means it contains only the
same substance.
Substance- matter with the same fixed
composition and properties.
 Can
be an element or a compound
 Any sample of pure matter is a substance
Substances
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The bag of sugar you buy at the store is
pure sucrose. It all has the same
properties and a fixed composition.
Therefore, it is a substance.
Mixed Matter
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Mixed matter is referred to as a mixture.
Mixture- combination of two or more substances
in which the basic identity of the substances are
not changed.
Mixtures do not have a specific composition.
Mixtures can be separated into its components
by physical means.
Separating Mixtures
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One way is by physical changes.
Physical change- a change in matter that does
not involve a change in the identity of individual
substances.
 Boiling
 Freezing
 Melting
 Evaporation
 Dissolving
 Crystallization
Physical Properties
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Separation by physical changes takes advantage of the
physical properties of the mixture.
Physical properties- characteristics that a sample of
matter exhibits without any changes in its identity
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Solubility
Melting and boiling point
Color
Density
Electrical conductivity
Physical state (solid, liquid or gas)
Types of Mixture
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There are two types of mixtures:
 Heterogeneous
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Hetero means “different”
 Homogeneous
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Homo means “the same”
Heterogeneous Mixture
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Heterogeneous Mixture- a mixture that
does not have a uniform composition.
 You
can see the different composition.
 Examples:
Granite
 Chef Salad
 Lucky Charms Cereal
 Orange Juice with pulp
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Homogeneous Mixture
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Homogeneous Mixture- a mixture with a uniform
composition.
 You
cannot tell that it is composed of more than one
substance
 Another name is a solution
 Examples:
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Salt water
Tea
Sugar water
Solutions
Homogeneous mixture
 Examples:
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 Salt
water
 Gasoline
 Air
 Steel
Alloys
Alloys- solid solutions that contain different
metals and sometimes nonmetallic
substance
 Table 1.1 page 23
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Table 1.1 Some Common Alloys
Name of Alloy
% Composition
Stainless Steel
73-79% iron (Fe)
14-18% chromium (Cr)
7-9% nickel (Ni)
Bronze
70-95% copper (Cu)
1-25% zinc (Zn)
1-18% tin (Sn)
Brass
50-80% copper (Cu)
20-50% zinc (Zn)
Sterling Silver
92.5% silver (Ag)
7.5% copper (Cu)
14-karat gold
58% gold (Au)
14-28% silver (Ag)
14-28% copper (Cu)
18-karat white gold
75% gold (Au)
12.5% silver (Ag)
12.5% copper (Cu)
Solder (electronic)
63% tin (Sn)
37% lead (Pb)
Solutions
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When you are dissolving a substance into
another substance there are two important
terms:
– the substance being dissolved
 Solvent – the dissolving agent
 Solute
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Salt Water
 Solute
= NaCl
 Solvent = H2O
Aqueous Solution
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Aqueous Solution- a solution in which the
solvent is water.
Examples:
 Soda
 Tea
 Contact-lens
cleaner
 Clear cleaning liquids
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Most processes of life take place in aqueous
solutions.
Substance: Pure Matter
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You and everything around you is made
up of chemicals.
Elements: The Building Blocks
If you classify an unknown piece of matter
as pure; it means that it is made up of one
substance
 There are two types of substances
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 Compounds
 Elements
Elements
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Elements- a substance that cannot be broken
down into simpler substances.
Simplest form of matter
Building blocks for other types of matter
All substance in the universe are:
 Elements
 Compounds
formed from elements
 Or mixtures of elements and compound
Elements
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118 elements
Examples:
 Gold
 Carbon
 Lead
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Elements combine to form millions of
compounds.
Chemical elements are often referred to as the
building blocks of matter
Elements
118 elements
 90 occur naturally
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 Less
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than half of these are abundant
The remainder are synthesized
Organizing the Elements
Elements are organized in the Periodic
Table
 The periodic table tells you:
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 Name
 Symbol
 Atomic
mass
Symbols
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The symbols of the elements are extremely
important to know.
You will only have to know the most common
ones.
The symbols are a one to two letter
representation of the elements.
Not all the symbols are the first or second letter
of the elements name
Symbols
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Oxygen
O
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Hydrogen
H
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Bromine
 Br
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Chlorine
 Cl
Table 1.2 Some Historic Chemical Symbols
Element
Symbol
Origin
Language
Antimony
Sb
Stibium
Latin
Copper
Cu
Cuprum
Latin
Gold
Au
Aurum
Latin
Iron
Fe
Ferrum
Latin
Lead
Pb
Plumbum
Latin
Potassium
K
Kalium
Latin
Silver
Ag
Argentum
Latin
Sodium
Na
Natrium
Latin
Tin
Sn
Stannum
Latin
Tungsten
W
Wolfram
german
Compounds Are More Than One
Element
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Compound – a chemical combination of two or
more different elements joined together in a
fixed proportion.
Every compound has its own fixed composition
Therefore, every compound has unique
chemical and physical properties.
The properties of a compound are different from
the properties of the elements that make them
up.
Compounds
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More than 10 million are known (still growing)
New natural compounds are being isolated from
plants and colonies of bacteria.
New compounds are also being synthesized in
labs.
Examples
 Sucrose
 Salt
 Water
Formulas of Compounds
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Formula – a combination of the chemical
symbols that show what elements make
up a compound and the number of atoms
of each element.
Sucrose:
Aspartame:
Table 1.3 Some Common Compounds
Compound Name
Formula
Acetaminophen
C8H9NO2
Acetic Acid
C2H4O2
Ammonia
NH3
Aspartame
C14H18N2O5
Propane
C3H8
Salt
NaCl
Sodium Hydroxide
NaOH
Sucrose
C12H22O11
Water
H2O
Review
What is the difference between an element
and a compound?
 What is the difference between a
homogeneous mixture and a
heterogeneous mixture?
 What is the difference between a mixture
and a compound?
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