Download Chapter III: Matter - Norwell Public Schools

Matter: Properties and
Changes
Chapter 3.1: Properties of Matter
Substances
• Review:
•
Matter is anything that has mass and takes up
space.
•
Matter with uniform and unchanging
composition is pure substance.
•
•
ie~ Table salt (NaCl)
What about H2O? Pure water = yes; seawater / tap water
= no.
Sates of Matter
• States of Matter
• All matter that exists can be classified
into one of three forms:
•
Each can be distinguished by the way it fills a container.
• Exception to rule: plasma (fourth state of
matter)
• Found in lightning bolts and stars.
Changes
States of Matter
3.1 Properties of Matter
• Solid
•
•
•
States of Matter
Definite shape and volume.
Particles tightly packed.
Expands slightly when heated.
Changes
States
of
Matter
3.1 Properties of Matter
• Liquid
States of Matter
•
Flows and has constant volume.
•
Particles not held in place and packed less
closely.
•
•
•
Able to move past one another.
Takes shape of container.
Expands when heated.
es
es of Matter
atter
States of Matter
• Gas
•
•
Flows to conform to shape of container & fills
entire volume.
•
Expands to fill containers.
Particles are very far apart
•
Easily compressible.
States of Matter
• Gases vs Vapor
•
•
Do not mean the same thing!
•
Vapor refers to gaseous state of substance that
is solid or liquid at room temperature
Gas is a substance that is naturally in the
gaseous state at room temperature.
•
Helium? Neon? Steam?
Physical Properties of Matter
•
Characteristic that can be observed or measured
without changing the composition.
•
•
Also describe pure substances.
•
Uniform and unchanging compositions = consistent and
unchanging properties.
Examples include: Density, color, odor, hardness,
melting point, boiling point.
Physical Properties of Matter
•
Two Types
•
•
Extensive
•
Dependent on the amount of substance present.
Examples include: Length, mass, & volume.
Physical Properties of Matter
•
Two Types
•
•
Intensive
•
•
Independent on the amount of substance present.
Examples include: Density- always the same regardless of
how much substance is present.
Substances can be identified by intensive
properties.
•
ie~ scent
Chemical Properties of Matter
•
The ability of a substance to combine with or
change into one or more other substances.
•
Composition of substance changes.
•
Results from contact with other substances or addition of
Chemical Properties energy (thermal or electric).
•
Example: Iron = Forms rust when in contact with oxygen in air
•
Copper =
Chemical Properties of Matter
•
Each substance has its own unique set of physical
and chemical properties.
•
Chemical Properties -
Copper: Can be shaped into different forms
(physical) or turns green when in contact with
air (chemical)
Matter: Properties and
Changes
Chapter 3.2: Changes in Matter
Changes in Matter
• Physical Change
• Changes in appearance but not
composition.
• Examples include: 1) Cutting sheet of
paper 2) Breaking glass object 3)
Crumpling piece of aluminum foil
Changes in Matter
• Phase Change
•
Transition of matter from one state to another.
•
Depends on temperature and pressure of
surroundings.
•
•
As temperature and pressure change, substances change
from one phase to another.
Example is the water cycle:
•
1) Ice (solid) is heated to become liquid water. 2) Add more
heat, liquid water boils and is converted to steam (gas).
•
What type of changes are these? Physical (Different appearance
but same composition)
Changes in Matter
• Phase Change
•
Melting and Boiling Points
•
The temperature and pressure at which a substance
undergoes a phase change.
•
Intensive physical properties that can be used to
identify unknown substances.
Changes in Matter
• Chemical Change
•
•
One or more substances changing into new
substances.
•
aka~ chemical reaction
New substances formed have different
compositions and properties.
Changes in Matter
• Chemical Reaction
• Starting substances = reactants.
•
New substances formed = products.
emical change -
Changes in Matter
• Chemical Reaction
•
Evidence
includes a change in properties.
idence of Chemical
Change
•
ie~ spoiled food: What are some changes in
properties? Look, taste, digestability...
Changes in Matter
• Law of Conservation of Mass
•
Mass is neither created nor destroyed during a
chemical reaction.
•
•
It is conserved.
•
mass of reactants = mass of products.
Although chemical changes occur, total mass
remains constant.
Changes in Matter
Law of Conservation of Mass
•
Law of Conservation of Mass -
•
Mass is neither created nor destroyed during a
chemical reaction.
A 10.0 g sample of magnesium reacts with oxygen to form 16.6 g of Magnesium
oxide. How many grams of oxygen reacted?
Matter: Properties and
Changes
Chapter 3.3: Mixtures of Matter
Changes in Matter
• Most everyday matter occurs as mixtures.
•
Combination of two or more pure substances.
•
Each pure substance retains its individual chemical
properties.
•
Composition of mixtures is variable.
Changes in Matter
• Types of Mixtures
•
Heterogeneous
•
•
•
•
Mixture that does not blend smoothly.
Composition is not uniform.
Substances remain distinct.
Examples include: salad dressing, orange
juice, etc.
Changes in Matter
• Types of Mixtures
•
Homogeneous
•
•
Has constant composition throughout.
•
Always has single phase.
Referred to as solutions.
Changes in Matter
• Solutions
•
•
Most familiar with liquid forms.
•
Examples include: tea, lemonade, etc
Solution systems can be solid, liquid, or gas.
•
Solid-solid solutions of metals are known as alloys.
•
Examples include: steel, bronze, 14-karat gold.
Changes in Matter
Homogeneous Mixture (solution) -
• Solutions
Separating Mixtures
• Important to be able to separate mixtures
to understand nature of matter.
• Use physical processes to separate
mixtures based on physical properties.
• ie~ magnet to separate metal
from sand.
MixturesSeparatingSeparating
Mixtures
• Filtration
•
Filtration -
Separates heterogeneous mixtures composed of solids
and liquids.
•
Uses a porous barrier.
Separating Mixtures
• Distillation
•
•
Used to separate most homogeneous mixtures.
Distillation -
Based on differences in boiling points.
1) Mixture is heated until lower boiling
point boils to vapor.
2) Vapor is condensed into liquid and
collected.
Separating Mixtures
• Crystallization
•
Results in the formation of pure solid particles of a
Crystallization substance.
•
Solid particles come from solution containing
dissolved substance.
•
•
Solids are highly pure
Example: rock candy
Separating Mixtures
• Sublimation
•
Sublimation
Solid changes to vapor without going through liquid
•
Used to separate one solid that sublimates form one
that does not.
phase.
Separating Mixtures
• Chromatography
•
Chromatography
Separates components
of a liquid mixture
(mobile
phase) based on ability of each to travel across
another material (stationary phase).
•
Components flow through stationary phase at
different speeds.
Matter: Properties and
Changes
Chapter 3.4: Elements and Compounds
Elements & Compounds
•
•
Matter can take many different forms.
•
All matter can be broken down into basic building
blocks called elements.
Element is a pure substance that cannot be
separated into simpler substances by physical or
chemical means.
•
•
92 natural elements
Several others that have been developed
Elements & Compounds
•
•
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Elements have unique chemical names & symbols.
•
Names consist of 1/2/3 letters.
•
First ALWAYS capitalized; rest are lowercase.
92 natural elements not evenly distributed.
•
•
H2: 75 % of mass of universe.
O2, H2, C: 90% of human body
Under normal conditions, elements can be found in each
type of phase. (ie~ Cu, Hg, He)
Elements & Compounds
•
Elements organized into a periodic table.
•
•
•
Based on similarities and masses
Rows = periods
Columns = groups / families
•
Elements in same group have similar chemical and physical
properties.
Elements & Compounds
•
Compounds made up of two or more different
elements that are chemically combined.
•
•
Most matter in the universe exists as compounds.
•
10 million known; ~ 100,000 developed each year.
Chemical formulas of compounds
•
Composed of chemical symbols and subscripts.
•
•
Subscripts indicate number of elements in each compound.
ie~ H2O, NaCl
Elements & Compounds
•
Compounds can be broken down into simpler
elements by chemical means.
•
Compounds generally more stable than individual
elements.
•
•
Requires energy (ie~ heat or electricity).
Electrolysis is breakdown of H2O.
*** What do you notice about the amount
of H2 compared to the amount of O2?
Properties of Compounds
•
Properties of a compound are different from those
of the individual elements.
•
ie~ H2O
•
How is H2O different than H2 & O2?
Properties of Compounds
•
Properties of a compound are different from those
of the individual elements.
Properties of Compounds vs. Elements
Properties of Compounds
• Organization of Matter
• Pure substances & mixtures.
• Separation???
Law of Definite Proportions
•
Elements in compounds combine in definite
proportions by mass.
•
Law of Definite Proportions = Compound is
composed of same elements in the same
proportion by mass.
•
Mass of the compound = sum of masses of
elements that make up the compound.
Law of Definite Proportions
Definite Proportions -
•
Law of Definite
Proportions
- in a compound can be
Amounts
of elements
expressed as percent by mass.
•
Ratio of the mass of each element to the total mass
of the compound.
A 1.0 g sample of hydrogen reacts with 19.0 g of fluorine. What is
the % of hydrogen in the compound?
sample of hydrogen reacts with 19.0 g of fluorine. Wh
of hydrogen in the compound?
Law of Definite Proportions
•
Amounts of elements in a compound can be
expressed as percent by mass.
•
Ratio of the mass of each element to the total mass of the
compound.
•
Percent by mass the same regardless of amount of
sucrose; each has the same mass proportion
Law of Multiple Proportions
•
Use when comparing different compounds
composed of the same elements.
•
Law of Multiple Proportions = Different
compounds are formed by a combination of the
same elements, different masses of one element
combine with the same relative mass of the other
element in a ratio.
one element combine with the same relative mass of the other
element in a ratio of small whole numbers
Law of Multiple Proportions
mass ratio of Compound I
1.793 g Cu / g Cl
=
= 2.000
mass ratio of Compound II
0.8964 g Cu / g Cl
• Mass ratio of copper to chlorine in Compound 1 is exactly two
times the mass ratio of copper to chlorine in Compound II.
• 2:1
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