Download Matter: Properties & Changes

Matter:
Properties & Changes
Chapter 3
3.1 Properties of Matter
 Matter is very diverse—we must begin to
organize and describe it.
What is a substance?
pure; has an unchanging composition
Examples of a substance include…
Water
table salt
& gasoline
What is not a substance?
 Sea water
Air
 What is a physical property?
 A characteristic that can be
observed/measured without changing the
composition
 Examples…
 Examples… shape, weight, color,
density, odor, taste, hardness,
melting/boiling point.
 (If they have consistent composition=
they have consistent phys property.)
2 types of phys properties
Extensive property dependent on the
amount of sub
 Ex.
Intensive property independent of the
amount of sub
 Ex.
Gold miners… gold vs. fools gold
 What is a chemical property?
 Ability of a substance to combine with of
change into one or more other substances.
 Examples…
iron
 1. iron forming rust when combined with
air.
 2. iron has no reaction with nitrogen gas.
 What are some physical properties of copper?
 What are some chemical properties of copper?
What are some phys/chem
properties of water?
 Phys. prop.
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Chem. prop.
Reacts with metals
Good solvent
pH
States of Matter
States of Matter
 Solid- will not conform to a
container
 Definite shape?
yes
 Definite volume?
yes
 Examples…
 How are particles
arranged?
Tightly packed
 Particle movement?
No (very little)
States of Matter
Liquids- matter that flows
Definite shape?
no
Definite volume?
yes
Examples…
How are particles
arranged?
They are less closely packed
Particle movement?
yes
States of Matter
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
Gases- matter that flows
Definite shape?
no
Definite volume?
no
Examples…
How are particles arranged?
Very far apart
Particle movement?
yes
Fills entire container?
yes
Compressed?
Very compressible
Gas versus Vapor
GAS
 Naturally gaseous
Ex.
Oxygen gas
VAPOR
 A gaseous STATE of
a substance
 Normally solid/liquid
at room temperature
 Ex.
steam
3.2 Changes in Matter
 Physical changes- changes that do not
alter the composition of a substance.
 Ex…
Physical changes
 Keywords…

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
bend
grind
crush
Melt
freeze
boil
vaporize
condenses
 Chemical changes- one or more
substances changes into other
substances; aka CHEMICAL REACTION
 Examples… HgO  Hg + O2
Chemical change
 Keywords…

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
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Explodes
Rusts
Oxidizes
Corrodes
Tarnish
Ferment
Burn
Rot
Chemical change
 Evidence of chem rxn… pg 63

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
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color change
puts off heat
odor change
Solid is formed
Forms gases.
Conservation of mass
 Conservation of mass Mass is neither created nor destroyed in any
process, it is conserved. (Mass is recycled.)
Antoine Lavoisier

(1743-1794)
Conservation of Mass
Mass reactants = Mass products
Ex. HgO (s) Hg (l) + O2 (g)
216 g  200 g + ?
Reactant
Products
(before rxn)
(after rxn)
 Ex. In an experiment, 10.00 g red mercury (II)
oxide powder is heated in a test tube where it
forms liquid mercury & oxygen gas. 9.26 g of
liquid mercury was recovered. What is the
mass of oxygen formed?
 ** practice problems 6-9
3.3 Mixtures of Matter
 What are two broad categories of matter?
 Substance & mixtures
 What is a mixture?
 Combination of multiple sub
2 types of mixtures:
 1. Heterogeneous mixture- (not blended
smoothly)(can be sep. by phys. means)
 Ex…




Sand & water
Ketchup
Oil & water
Others?
2 types of mixtures:
 2. Homogeneous mixtures- (blended
smoothly)(can be sep. by phys.means)
 A.k.a. “Solutions”
 Ex…
Ex…
Type of solution Example:
gas- gas
gas- liquid
liquid- gas
liquid- liquid
solid- liquid
solid- solid
 List 4 ways to separate mixtures.
1. Filtration- separates solid from liquid
Ex.
2. Distillation- sep. solution of 2 liquids b/c of
different boiling pt.
Ex.
3. Crystallization- sep of dissolved solid from
solution
Ex.
4. Chromatography- sep. components of a
mixture by travelling
Ex.
3.4
Elements & Compounds
 What is an element?
 A pure sub that cannot be further broken down
 Ex… Na, N, Ca, O etc
 What is a chemical symbol?
 How many naturally occuring element are
there?
 91
 H>Fr
3.4
Elements & Compounds
 What was Dmitri Mendeleev’s most significant
contribution to chemistry?
 Chart that organized elements into rows & columns
based on similarities.
 Horizontal rows are called “periods”
 Vertical rows are called “groups” or “family”
 Elements of the same group have similar
physical & chemical properties.
3.4
Elements & Compounds
 What was so amazing about
Mendeleev’s table?
 He left blanks b/c he predicted that there
were more elements that haven’t been
discovered yet.
3.4
Elements & Compounds
 What is a compound?
 A substance consisting of 2 or more
elements.
 Ex… H2O, NaCl, CO2
 Compounds can be broken down by
chemical means.
3.4
Elements & Compounds
 Can water be decomposed?
 Yes, electrolysis
 Are the properties of a compound the
same as the elements of which it is
composed?
 NO
 Ex.
 Sodium- metal solid, soft, highly reactive
with water
 Chlorine- gas, yellowish, poisonous
 Salt- crystal solid, hard, white, harmless




Ex.
Oxygen- flammable, for respiration
Hydrogen- flammable
Water- not flammable
 What is the Law of Definite Proportion?
 Regardless of mass, a comp. will always
have the same proportion.
 Formula for calculating percent by mass:
mass of element X 100% = % by mass
mass of compound
% by mass example
 Ex. 1
 The mass of carbon in a 20.0g sample of
sucrose (sugar) is 8.4g. What % by mass is
carbon?
% by mass example
 Ex. 2
 You have a 500. g sample of sucrose.
Carbon in this sample has a mass of 210.5g.
What percent by mass is carbon?
** Practice problems p. 76 #20-23
 What is the law of Multiple proportions?
 Chemicals with different ratios of elements
are different compounds.
 Can compounds composed of the same
element be different compounds?
 Yes. If they have different mass ratios
 Ex. H20- water
H2O2 – hydrogen peroxide
 STOP