Transcript Chapter 1 Chemistry: The Study of Matter

Honors Chemistry
course syllabus on my
web page
1
Chapter 1
Matter and Change
2
Objectives:
 Describe the difference between a physical change and a
chemical change and give several examples of each.
 Describe different characteristics of the three states matter.
 Classify a mixture as homogeneous or heterogeneous.
 Classify a pure substance as an element or a compound.
 Identify methods of separations of mixtures.
 State the laws of conservation of mass and energy.
3
Chapter 1
Section 1
Chemistry is a Physical Science
4

Chemistry is the study of matter and the
changes it undergoes.
Biological
Science
Chemistry
Physical
Sciences
Chemistry is central to all sciences.
Both living and non living matter have
a chemical structure.
5
Chemistry deals with:
1. What is matter made of?
2. What is the makeup and internal
arrangement of the atoms?
3. How does it behave when heated,
cooled or mixed with other materials?
6
Branches of Chemistry
Organic chemistry – the study of carbon
containing compounds.
Inorganic chemistry – the study of
substances that do not contain carbon
(metals and gases).
Physical chemistry – the study of the
properties and changes of matter and their
relation to energy.
7
Analytical chemistry –the identification of the
components and composition of materials.
Biochemistry – the study of the processes
occurring in living systems.
8
Types of Research
9

Basic Research - carried out for the
sake of increasing knowledge.

Most basic research is carried out in
universities.

Research is normally published in
scientific journals.
Types of Research
10

Applied Research - carried out to solve
a problem.

Research is carried out by companies to
make a profit.

Usually short term goals set by the
company.
Summary
1) Define the word chemistry.
2) Name the five branches of
chemistry.
3) Define basic and applied
research.
11
Chapter 1
Section 2
Matter and its Properties
12
What is Matter?
13

Matter is anything that takes up space
(volume) and has mass.

Mass is the amount of matter in an object.
Usually measured with a balance.

Volume is the amount of three
dimensional space an object occupies.
Building Blocks of Matter
14

The fundamental building blocks of
matter are atoms.

Atoms – the smallest unit of an element
that maintains the properties of the
element.

Element – a pure substance made of
only one kind of atom.
Element Examples – carbon, hydrogen
and oxygen.
The periodic table lists all the elements.
Elements contain only one kind of atom.
15
16

Compound – a substance that is made
from the atoms of two or more elements
that are chemically bonded.

Compound Examples – water (made of
hydrogen and oxygen), methane (made
of carbon and hydrogen) and sugar
(made from carbon, hydrogen and
oxygen).
H2O, CH4 and CxHxOx
Properties and Changes in Matter
Every substance, whether it is an element
or a compound, has characteristic
properties.
Chemists use properties to distinguish
between substances and to separate them.
Properties can help reveal the identity of
an unknown substance.
17
Properties and Changes in Matter
Properties can also be grouped into two
general types: physical and chemical.
Physical – a property that can be observed
or measured without changing the identity
of the substance.
Such properties include: color, shine,
hardness, melting point and boiling point.
18
Properties and Changes in Matter
A physical change in a substance does
not involve a change in the identity of the
substance.
Examples include: grinding, cutting,
melting and boiling the substance.
These changes do not change the
identity.
19
Chemical – a property that relates to a
substance’s ability to undergo changes that
transform it into different substances.
Such properties include: burning of wood,
rusting of iron (Fe2O3) and tarnishing of
silver.
When charcoal (carbon) burns, it combines
with oxygen in the air to form carbon
dioxide. The charcoal and oxygen no
longer exists in their original form.
20
Properties and Changes in Matter
A chemical change is when a substance
is converted into a different substance.
The substances that react (starting
material) in a chemical change are called
the reactants.
The substances that are formed by the
chemical change are called the products.
21
Properties and Changes in Matter
In the example of burning of charcoal,
carbon and oxygen are the reactants in the
combustion reaction. Carbon dioxide is
the product.
carbon + oxygen
C
+
O2
(reactants)
22
carbon dioxide
CO2
(product)
Problem
Would the dissolving of sugar in water be
a physical or chemical change?
23
Answer
Dissolving of sugar into water is a
physical change.
If you were to evaporate the water from
the container you would be left with
sugar. It has not changed to a different
substance.
24
Indications of a chemical reaction
Energy absorbed or released
 Color change
 Odor change
 Precipitate - solid that separates from
solution
 Not easily reversed

25
States of Matter
The three common states of Matter:
Solid
Liquid
Gas
26
Solid State – matter in the solid state has
definite volume and shape.
The particles that make up the solid are
packed close together in relatively fixed
positions.
The particles are held close together by
strong attractive forces.
27
Liquid State – matter in the liquid state has
definite volume but an indefinite shape.
A liquid assumes the shape of its
container. The particles that make up the
liquid are packed close together but can
move past one another.
The rapidly moving particles cause them to
temporarily overcome the attractive forces
between them, allowing the liquid to flow.
28
Gas State – matter in the gas state has no
definite volume nor shape.
Gases have this characteristic because
they are composed of particles that move
very rapidly and are at great distances
from one another.
At these distances, the attractive forces
are very weak. A gas will expand to fill any
size container and take the shape of that
container.
29
Condense
Freeze
Evaporate
Melt
Solid
30
Liquid
Gas
Law of Conservation of Mass
Mass can not be created or destroyed in
ordinary (not nuclear) changes.
 All the mass can be accounted for.
 Mass at the start = mass at end

31
Energy and Changes in Matter
When physical or chemical changes
occur, energy is always involved.
The energy can take the form of heat or
light.
Heat provides enough energy to cause
physical changes – melting of ice.
32
Types of Matter

All matter can be classified into one of
two groups: pure substances or
mixtures.
Pure Substance – can be an element or
compound. The composition of a pure
substance is the same throughout and
does not vary from sample to sample.
 Examples include: water, sugar, gold
and aluminum.

33
34

Mixture – contains more than one
substance.

They can vary in composition and
properties from sample to sample.

Examples include: sugar dissolved into
water, granite, brass, chocolate chip
cookie and air.
Mixtures
Homogeneous- same composition
throughout. Homogenous mixtures are
also called solutions.
 Example: salt water solution and air

Heterogeneous- mixture is not the same
throughout the sample.
 Example: sand and water. The heavier
sand settles to the bottom.

35
Solutions
Homogeneous mixture
 Can occur between any state of matter.
 Solid in liquid- Kool-aid
 Liquid in liquid- antifreeze in a car radiator
 Gas in gas- air (oxygen, nitrogen and
argon)
 Solid in solid - brass
 Liquid in gas- water vapor

36
Separating mixtures
Only a physical change- no new matter
 Filtration - separate solids from liquids
with a barrier (filter paper)


37
Distillation - separate liquids because of
different boiling points
– Heat mixture
– Catch vapor in cooled area
38
39
Pure Substances
In contrast to a mixture, a pure
substance is always homogeneous.
 A pure substance has a fixed
composition.
1) Every sample of a given pure
substance has exactly the same
characteristic physical and
chemical properties.
2) Every sample of a pure substance
has exactly the same composition.

40
Pure Substances
Pure substances are either elements or
compounds.
A compound can be broken down, or
decomposed, into two or more simpler
elements by a chemical change.
Water is made from hydrogen and oxygen
atoms bonded together. H2O
41
Pure Substances
Water can be broken down into the
hydrogen and oxygen atoms through a
chemical reaction called electrolysis.
This involves passing an electric current
through water.
When broken down, water contains 11.2%
hydrogen and 88.8% oxygen
42
Pure Substances
Sucrose (sugar) is made of carbon,
hydrogen and oxygen.
Sucrose breaks down into carbon and
water when heated to high temperatures.
43
Summary
44
Classwork
Page 18: Questions 1, 2 and 4
45
Homework
Page 26:
Questions: 2, 4, 5, 6, 9, 10, 11, 12 (a-c) and
13
46
Chapter 1
Section 3
Elements
and the
Periodic Table
47
Element – a pure substance made of only
one kind of atom.
Element – pure substance that cannot
be decomposed by chemical changes.
Elements serve as the building block of
matter.
Each element has characteristic properties.
48
Periodic Table
Elements – are organized into groups
based on similar chemical properties.
Periodic Table – The organization of
elements is the periodic table.
Each box on the periodic table lists one
element and the letter symbol.
49
Chemical Symbols
There are 111 elements
 Each has a 1 or two letter symbol
 First letter always capitalized second
never
 Don’t need to memorize
 Some from Latin or other languages

50
Chemical Symbols
Used to write chemical formulas
 Subscripts tell us how many of each
atom
 H 2O
 C 3H 8
 H2CO3

51
Periodic Table
Groups or Families – the vertical columns
of the periodic table.
The groups are number 1 to 18 from left to
right.
Each group contains elements with similar
chemical properties.
52
Periodic Table
Alkaline Earth Metals – Group 2 of the
periodic table.
Elements include beryllium, magnesium,
calcium, strontium, barium and radium.
All of these elements are reactive metals
with similar bonding abilities.
53
Noble Gases
Noble Gases - the elements in Group 18
of the periodic table.
 They are considered nonmetals.
 These elements are generally
unreactive.
 All are gases at room temperature.
 Examples: neon, argon, krypton, xenon
(all used in lighting) and helium.

54
Periodic Table
Periods – the horizontal rows of elements in
the periodic table.
Physical and chemical properties change
across a period.
Elements on opposite sides of the periodic
table in the same row are much different.
Example is lithium and fluorine in Period 2.
55
Types of Elements
56

The periodic table is broadly divided into
two main sections: metals and
nonmetals.

The metals are at the left and the center
of the table.

The nonmetals are toward the right.
Metals
57

Metal – an element that is a good
conductor of heat and electricity.

Properties: solids (mercury), shines,
malleable (hammered), ductile (drawn
into thin wires), resistance to breaking,
conductors of heat and electricity.
Nonmetals

Nonmetal – an element that is a poor
conductor of heat and electricity.
Properties:
 Gases – nitrogen, oxygen, fluorine and
chlorine.
 Liquids – bromine
 Solids – carbon, phosphorus, sulfur, iodine

58
Nonmetals

Properties:
The solids tend to be brittle rather than
malleable or ductile.
 Low conductors of heat and electricity.

59
Metalloids
60

Metalloids – an element that has some
characteristics of metals and nonmetals.

A stair-step line separates the metals
from the nonmetals on the periodic
table.
Metalloids
Properties:
 All metalloids are solids at room
temperature.
 Less malleable than metals but not as
brittle as nonmetals.
 Metalloids tend to be semiconductors of
electricity. (intermediate between metals
and nonmetals).

61
Metalloids
Properties:
 Metalloids are used in semiconducting
materials found in computers,
calculators, televisions and radios.


62
Elements include: boron, silicon,
germanium, antimony
Homework
Page 26:
Questions: 14, 15, 17, 18, 19, 20 and 23
63
End of Chapter 1
64
Energy
The ability to do work.
 Work - cause a change or move an
object.
 Many types- all can be changed into the
other.

65
Types of Energy
Potential- stored energy
 Kinetic Energy- energy something has
because its moving
 Heat- the energy that moves because of
a temperature difference.
 Chemical energy- energy released or
absorbed in a chemical change.
 Electrical energy - energy of moving
charges

66
Types of Energy
Radiant Energy- energy that can travel
through empty space (light, UV,
infrared, radio)
 Nuclear Energy – Energy from changing
the nucleus of atoms
 All types of energy can be converted
into others.
 If you trace the source far enough back,
you will end up at nuclear energy.

67
Conservation of Energy
Energy can be neither created or
destroyed in ordinary changes (not
nuclear), it can only change form.
 Its not just a good idea, its the law.

68
What about nuclear?
E = mc2
2
 energy = mass x (speed of light)
8
 speed of light = 3 x 10
 A little mass can make a lot of energy
 Law of Conservation of Mass - Energy
the total of the mass and energy
remains the same in any change

69