CP Chemistry
THHS 2014-2015
Section 2.1 Matter
 Objectives
 Identify the characteristics of matter and
substances
 Differentiate among the three states of matter
 Define physical property and list several
common physical properties of substances
Properties of Matter
 Matter
 anything that has mass and takes up space.
 Mass
 The amount of matter the object contains.
 Note mass ≠ weight.
 Substance
 Pure substances contain only one kind of matter.
 Question – is lemonade a substance?
Physical Properties
 Physical Property – a quality or condition of a
substance that can be observed without changing
the substance’s composition.
 Examples of physical properties are color,
solubility, odor, hardness, density, melting point,
and boiling point.
Properties of the States of Matter Solid, Liquid and Gas
Property
Solid
Liquid
Gas or vapor
Shape
Definite
Indefinite
Indefinite
Volume
Definite
Definite
Indefinite
Expansion on
heating
Very slight
Moderate
Great
Compressibility
Almost
incompressible
Almost
incompressible
Readily
compressible
Properties of Solids, Liquids, Gases
 Solid
 Has a definite shape and volume
 Does not depend on the shape of its container
 Almost incompressible
 Liquid
 Particles are in close contact but not rigidly packed
 Can flow and take the shape of the container it is in
 A fixed volume can take a variety of shapes
 Almost incompressible
Properties of Solids, Liquids, Gases
 Gas or vapor
 “Gas” is limited to those substances who are in a
gaseous state at room temperature.
 “Vapor” describes the gaseous state of a
substance that is a liquid or a solid at room
temperature. An example is steam.
 Gases take the shape of the container they are in.
 Particles are spaced far apart.
 Gases expand without limit to fill any space, so its
volume changes with the container, unlike liquids.
 Gases tend to expand when heated.
Physical Changes
 A change which alters a given material without
changing its composition is called a physical
change
 Examples are cutting, grinding, bending
 Melting a metal, melting ice, boiling water
 Boil, freeze, dissolve, melt, condense, break,
split, crack – all examples of physical changes
Section 2.2 - Mixtures
 Objectives
 Categorize a sample of matter as a substance or a
mixture
 Distinguish between homogeneous and
heterogeneous samples of matter
Classifying Mixtures
 A mixture is a physical blend of two or more
substances.
 Salad with lettuce, tomatoes, carrots
 Blood – with water, cells, chemicals
 Each of these mixtures can vary in composition
 Heterogeneous mixture – if you were to sample the
mixture in two different places the composition
wouldn’t be the same (salad)
 Homogeneous mixture – if you were to sample the
mixtures in two different places, the composition
would be the same (salt water)
 Homogeneous mixtures are called solutions.
Phases in Mixtures
System
Examples
Gas- gas
Carbon dioxide and oxygen in nitrogen (air)
Liquid – gas
Water vapor in air (moist air)
Gas – liquid
Carbon dioxide in water (soda water)
Liquid- liquid
Acetic acid in water (vinegar)
Solid – liquid
Sodium chloride in water (salt water or brine)
Solid – solid
Copper in silver (sterling silver, an alloy)
• Phase – any part of a system with uniform
composition and properties is a phase.
• Homogeneous mixtures are one phase.
• Heterogeneous mixtures are two or more
phases.
• Oil and vinegar separates into two phases
Separating Mixtures
 Some mixtures can be separated by physical
methods.
 Magnet to separate iron filings from sulfur.
 Distillation can be used to separate pure water
from impurities.
Section 2.3 –
Elements and Compounds
 Objectives
 Explain the difference between an element and a
compound.
 Identify the chemical symbols of common
elements, and name common elements given
their symbols
Elements vs. Compounds
 Elements are the simplest forms of matter that can
exist under normal laboratory conditions.
 This statement does not include the subatomic level
(protons, neutrons, etc.)
 Elements cannot be separated into simpler substances
by chemical means .
 Examples: Oxygen, carbon, nitrogen
 Compounds are made when two or more elements
combine chemically, like H2O or CO2 .
 Compounds can be separated into simpler substances
by chemical means.
Compounds
 Example: Sodium chloride NaCl (table salt)
 Composed of Chlorine (which is the gas Cl2 as
an element) and Sodium (which is the solid Na
as an element)
 Anyone know why sodium (solid) is normally
stored in oil?
Quick Quiz
 Do you think gasoline is an element, a compound or a
mixture?
 If you had a uniform blue solid and heated it up in the
absence of air, and it formed a colorless gas and a white
solid – was the blue solid an element, a compound or a
mixture?
 A clear liquid is allowed to evaporate for 3 days and at
the end you find a solid residue – was the liquid an
element, compound or mixture?
Chemical Symbols
 Some chemical symbols are easy to remember
 Carbon = C, Oxygen = O, Nitrogen = N
 Others are not so easy, and come from Latin or other
sources
 Sodium = Na (from Natrium)
 Potassium = K (from Kalium)
 Gold = Au (from Aurum)
 Lead = Pb (from Plumbum)
 A list of more unusual symbols is on page 40 and on
my website for you to review!
 You will need to know at least the top 4 rows of the
periodic table - name and symbol
Section 2.4 – Chemical Reactions
 Objectives
 Differentiate between physical and chemical
changes in matter
 Apply the law of conservation of mass
Changing reactants to products
 Chemical reactions - one or more substances react
and change into a new substance
 Example: iron + oxygen = rust (iron oxide)
 The starting substances are called reactants
 The ending substances are called products
 Words that convey that a chemical change has
occurred include: burn, rot, rust, decompose, ferment,
explode, corrode, etc.
Chemical Properties
 Chemical properties tell you something about the
ability of a substance to undergo a chemical reaction to
form new substances
 Rusting is a chemical property of iron
 Rotting is a chemical property of waste organic material
 Burning is a chemical property of wood
Examples of chemical reactions
Chemical reactions
 How can you tell if a reaction has
taken place?
 Energy is always given off or
absorbed during a reaction
 Change in color or odor –
 silver chromate forms when yellow
sodium chromate is added to clear
silver nitrate (above right)
 Production of gas or solid from a
liquid
 zinc + hydrochloric acid releases
H2 gas >>>
 Most chemical changes are not easily
reversed, like many physical changes
are.
Conservation of Mass –
Key concept
 When you burn wood at a beach bonfire, the reaction
produces carbon dioxide gas (CO2), water vapor (H2O)
and some ash.
 It may seem that the amount of matter has been
reduced when you look at the ash pile.
 However, if you could carefully measure the mass of
the reactants and the mass of the products, you would
find they are the same.
 This is the law of conservation of mass – mass is
neither created or destroyed in a chemical reaction.
Conservation of Mass
 Let’s say you have 32 grams of methane(CH4) that
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combine with 128 grams of oxygen gas to form 88
grams of carbon dioxide and an unknown number of
grams of water.
How much water is formed?
.
𝐶𝐻4 + 2𝑂2 𝐶𝑂2 + 𝐻2 𝑂
32 + 128 = 88 + x grams
Solve for x
x = 32 + 128 - 88 = 72 g
This is because mass of total reactants must equal
mass of total products.
Chapter Review:
Quick Quiz 2.1
 Contrast the characteristics of the three states of
matter.
 Solids have a definite shape and volume and are
nearly incompressible.
 Liquids have a definite volume but no definite
shape, and are nearly incompressible.
 Gases have neither definite shape nor volume
and are easily compressed, and expand without
limit when heated.
Quick Quiz 2.2
 Explain the difference between a homogeneous
and heterogeneous mixture.
 Homogeneous mixtures have a uniform
composition throughout the sample.
 Heterogeneous mixtures have a non-uniform
composition consisting of two or more phases.
Quick Quiz 2.3
 What are the chemical symbols for the following
elements? Copper, oxygen, silver, sodium,
phosphorus, helium.
 Cu, O, Ag, Na, P, He
 What are the chemical elements that have the
following symbols? Sn, Ca, S, Cd, K, Cl
 Tin, Calcium, Sulfur, Cadmium, Potassium, Chlorine
Quick Quiz 2.4
 Classify the following changes as physical or chemical:
 Cookies are baked
 chemical
 Water boils
 physical
 Soap dissolves in water
 physical
 A firefly emits light
 chemical
 Milk spoils
 chemical
 A metal chair rusts
 chemical
 What is the definition of a substance?
 Matter that has a uniform and definite composition.
 A physical blend of two or more substances is called
what?
 Mixture
 Substances that can be separated into simpler
substances only by chemical reaction are called what?
 Compounds
 Any part of a system with uniform composition and
properties is called what?
 A phase