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 H O? Pure water = yes; seawater / tap water =
no.
2
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!
• Gas is a substance that is naturally in the gaseous
state at room temperature.
• Vapor refers to gaseous state of substance that is
solid or liquid 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
solid particles of a
• Results in the formation of pure
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
phase.
• Used to separate one solid that sublimates form one
that does not.
Separating Mixtures
• Chromatography
Chromatography
- (mobile
of a liquid mixture
• Separates components
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
• 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.
• H : 75 % of mass of universe.
• O , H , C: 90% of human body
2
2
2
• 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~ H O, NaCl
2
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. W
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 of small whole numbers.
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
10