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Unit 1
Structure of Matter
The Known Universe
• Everything in the known universe can be
classified as either matter or energy.
− Matter describes the physical things
around us: the earth, the air you breathe,
your pencil.
− Energy is the ability to cause change or
do work: including light, heat, electrical
energy and mechanical energy, such as
Matter & Its Properties
• The definition of matter has two parts
− All matter has volume, which is the
3-D space an object occupies
− All matter has mass, which is a measure of
the amount of matter in an object.
Properties & Changes:
• There are 3 common states of matter
− Solids have definite volume & definite shape
o Particles are limited in their movement and packed
close together
− Liquids have definite volume but not definite
o Particles are able to move around each other yet are
still packed close together
− Gases have neither definite vol. nor shape
o Particles are independent of each other
Properties & Changes:
• There are 2 other states of matter that are
not as widely acknowledged
− Plasma is the result of superheating gases
− Supersolid or superfluid is the result of super-
cooling a solid (not much
known about it so far,
but lots of research
Classification of Matter
• All forms of matter (no matter what it
looks like) can be classified into one
of two categories
Classification of Matter
• Two categories:
− Pure substances
o Are uniform in composition
o Described by a chemical formula
− Mixtures
o Are composed of more than one
component blended together
o Different substances physically mixed
Classification of Matter: Pure Substances
• A pure substance has a fixed composition
− Every sample has exactly the same
− If they can be separated they can only be
separated by chemical change (elements can
not be broken down further)
− Can be identified by a unique chemical
formula: H, Ar, C, H2O, CO2, CH4, C6H12O6
Classification of Matter: Pure Substances
Pure Substances: Atoms
• Atoms are the most basic building blocks
of all matter.
− There are 110+ different kinds of atoms
o All 110+ atoms look identical and are
composed of the same types of pieces
called, subatomic particles
o However, an atom is mostly empty
• There are 3 subatomic particles and they
differ in their location in the atom, their
electrical charge and in their mass
Pure Substances: Atoms
− In the center of the atom is an extremely
dense core called the nucleus, which is
composed of protons and neutrons
o Protons are electrically positive, and make
up half of the mass of the atom
o Neutrons are electrically neutral, and make
up the other half of the mass of the atom
− Surrounding the nucleus is an electrically
negative “particle” called an electron
o We tend to visualize the space the electrons occupy
as a negatively charged cloud
Classification of Matter: Pure Substances
− An element is a pure substance made up of
only one type of atom
− Atoms can combine permanently together
to make up molecules
o A molecule is the smallest version of
chemically combined atoms
− Atoms combine to make up molecules,
atoms and/or molecules can combine to
make up mixtures
Classification of Matter: Mixtures
• Matter that isn’t pure must be a mixture
of pure substances
− The components in a mixture are simply
blended together physically, which means
they can be separated physically
− When pure substances are blended together
the components have the same properties
as when they are separate
o Melting point, boiling point, density, resistance to
chemical change, etc.
Your Turn…
• Classify each of the following as a mixture
or a pure substance
Table salt
Pure substance
Pure substance
Pure substance
Pure substance
Classification of Matter: Mixtures
− There are 2 types of mixtures:
o Heterogeneous mixtures
o Homogeneous mixtures
Mixtures: Homogeneous Mixtures
• Homogeneous mixtures are uniform in
− They have the same proportion of
components throughout
− This type of mixture is only composed of a
single phase
o Liquid, solid, gaseous, etc.
− AKA solutions
o For example salt water, brass, air, etc.
o Particle size at the ion, or molecule level, .1 –
2 nm.
Mixtures: Heterogeneous Mixtures
• Heterogeneous mixtures are not uniform
− Often have more than one phase
o gas and liquid, gas and solid, solid and liquid. . .
o e.g. Sea water, granite, blood, sand
Two categories:
①A heterogeneous mixture of large (visible) solid
particles in a liquid is called a
o e.g. jar of muddy water, paint, dust particles in air.
o Will settle over time.
o Particle size greater than 1000 nm
Mixtures: Heterogeneous Mixtures
②A mixture of smaller particles that don’t
settle out, but are still visible is called a
o e.g. Milk, smoke, fog
o 2-1000 nm
Your Turn…
• Classify each of the following as a
homogeneous or heterogeneous
The atmosphere
A carbonated soft drink
A solution of ethanol
and water
Mixtures: Separation Techniques
• All mixtures can be separated by some kind
of physical method
− Mixtures can be separated using several
techniques which have been developed
based on the type of mixture
Separation Techniques: Chromatography
• Chromatography is a technique that works
for separating dissolved solids or a mixture
of several liquids or even gaseous mixtures
− Chromatography makes use of 2 phases
to separate the mixture
o Stationary phase – the phase the mixture is
drawn across, it attracts each component in the
mobile phase differently
o Mobile phase – this phase contains the mix-ture
to be separated; each component flows across the
stationary phase at a unique rate
Separation Techniques: Distillation
• Distillation is an effective method of separating
a mixture of liquids or to purify a liquid with solid
particles dissolved in it
− Uses the differences in the boiling points of
different components in the mixture
− Each component boils at a different temperature,
therefore it is possible to boil off one liquid phase
of the mixture at a time.
• Distillation is used to purify alcohol, or water, or
refine oil
Separation Techniques: Crystallization
• Crystallization is a separation technique,
that produces a pure solid from a solidliquid solution
− Usually involves a
supersaturated solution
o Rock candy, stalactite
and mineral formation,
crystallized honey, etc.
Properties & Changes: Physical
• A physical property is a characteristic that
can be observed or measured without
changing the identity of the substance
− temperature, density, texture, color, shape,
taste, specific heat, strength, luster,
hardness, mass, odor, state, solubility,
conductivity, ductility, malleability, etc.
− It generally takes several phys properties to
identify a substance
Properties & Changes: Physical
• There are 2 types of physical properties:
− Intensive properties, which are properties
that do not depend on the amount of the
matter present.
o Color
o Odor
o Luster
o Malleable
o Ductile
o Conductive
o Hardness
o Melting Point
o Boiling Point
o Density
Properties & Changes: Physical
− Extensive properties, which are properties
that do depend on the amount of matter
o Mass
o Volume
o Area
o Energy
o Electrical Charge
o Momentum
Properties & Changes: Physical Changes
• A change in a substance that does not
include a change in the identity of a
substance is a physical change
− Grinding, melting, cutting, boiling, etc.
• Melting and boiling are part of an important
class of phys changes called changes of
− Change from one state of matter to
another (solid to liquid)
Properties & Changes: Chemical Changes
• A property that relates to a substance’s
ability to undergo changes that transform it
into different substances is known as a
chemical property
− Easier to see when substances react to form
new substances. e.g. the ability of charcoal
to burn, ability of iron to rust, ability of silver
to tarnish
• A change in which 1 or more substances are
converted into different substances is called
a chemical change or chemical reaction
Properties & Changes: Chemical Changes
• The substances that react in any chemical
rxn are called reactants
− They are the ingredients
• The results of the reaction are called
• An example of a chemical rxn
would be charcoal burning
− Carbon and oxygen would
be the reactants
− Carbon dioxide and water
are the products
Physical vs. Chemical Properties
A characteristic of a substance that can
be observed or measured without
changing composition.
Ex: density, color, shape, hardness,
melting & boiling points
2 kinds of phys properties;
Intensive and extensive
The ability of a substance to undergo
chem rxns and to form new substances
Ability to burn, to react, to decompose,
Your Turn…
• Classify each of the following as physical or
chemical changes
Moth balls gradually vaporize in a closet
Hydrofluoric acid attacks glass, and is used to
etch calibration marks on glass utensils
A French chef making a sauce with brandy is able
to burn off the alcohol from the brandy, leaving
just the brandy flavoring
Chemistry majors sometimes get holes in the
cotton jeans they wear to lab because of acid
Properties & Changes: Energy
• When physical or chemical changes occur,
energy is always involved
− Energy is the capacity to do work
• Energy can be released or absorbed
− It is transformed from one type to another,
o Chemical energy stored in charcoal is converted into
heat energy when ignited
• Both energy and matter are conserved
− They can neither be created nor destroyed
− These are called the Laws of Conservation of
Matter & Energy
Properties & Changes: Energy
• We will deal more with energy later, but
there are 8 different types
− Kinetic Energy
− Potential Energy
− *Light Energy
− Sound Energy
− Electrical Energy
− *Chemical Energy
− *Heat Energy
− Mechanical Energy
Pure Substances: Atoms
• The only obvious difference between one
type of atom and another are how many
electrons, protons, and neutrons the
different types of atoms have
Pure Substances: Elements
• Clusters of the same type of atoms are
called elements
− elements are pure substances that can’t
be decomposed
− Each element has features that make it
unique and cause it to behave in a
predictable manner
− They are collectively organized in a huge
chart called the periodic table (PT)
Pure Substances: Elements
• Each square on most Periodic Tables gives
information about the element that the
square represents.
Atomic Number
Atomic Symbol
Atomic Name
Atomic Weight
Sec 1-3
Pg 20-24
Pure Substances: Elements
− Atomic Number
o This number is the order that the atom is
on the Periodic Table
o It also represents the number of protons
that the atom has in its nucleus
− Atomic Symbol
o This is the symbolic representation of the
o This symbol is used when writing chemical
Pure Substances: Elements
− Atomic Name
o This is the name of the element, which may
be named from mythology, latin, scientist of
discovery, country of discovery, etc.
− Atomic Weight
o This is a measure of the mass
of the average atom of that element
o It’s equal to the mass of the nucleus of the
average atom of that element
Your Turn…
• Use the clue provided to identify the
Atomic number: 5
Symbol: Ga
Atomic weight: 12.011
Symbol: Pb
Atomic weight: 210
Atomic number: 84
Pure Substances: Organization of the PT
• The PT is organized into vertical columns
called groups or families.
− There are 18 columns
• Each group contains elements with similar
chemical characteristics
− for instance elements in group 2 are
reactive metals with similar abilities to bond
to other kinds of atoms
− Or group 18 which are all gases that are
extremely resistant to chemical change
Pure Substances: Organization of the PT
• The horizontal rows of elements in the PT
are called periods.
− Physical and chem characteristics change
predictably across the period
− Elements close to each other tend to have
similar characteristics, while elements
farther apart become increasingly different
o For example the elements on the far left
of the
PT tend to be soft, shiny solids that are good
o The far right are gases
Pure Substances: Organization of the PT
• The two sets of elements below the PT
make up what are called the lanthanide
and actinide series.
− They are metallic and radioactive and
should be placed after elements 57 & 89
Pure Substances: Organization of the PT
• There is another major division of the
elements, metals, nonmetals & metalloids.
Pure Substances: Organization of the PT
• A metal is a shiny element that is a good
conductor of heat and electricity
− At room temp, most metals are solids.
o Mercury is an exception, it’s standard state
is liquid (standard state is the state of matter
at 25 C and 1 atm)
− Most metals are also
o That is they can
be hammered or
rolled into thin sheets
Pure Substances: Organization of the PT
− Metals tend to be ductile.
o Which means they can be drawn into a fine
− Metals behave this way because of their
high tensile strength
o Tensile strength deals with its resistance
to breaking.
o The metal atoms just realign themselves as
the metal is being stretched or hammered.
Pure Substances: Organization of the PT
• Nonmetals are elements that are poor
conductors of heat and electricity
− Many nonmetals are gases at room
temperature (H, O, N, F, Cl)
− One nonmetal is a liquid (Br)
− The rest tend to be brittle solids
(C, S, P, Se, I).
Pure Substances: Organization of the PT
• Metalloids are elements that have some of
the characteristics of metals and some of
− on the stair step line that separates the
metals from the nonmetals
− All metalloids are solids at room temp
− Tend to be less malleable
than metals, but not as brittle
as nonmetals
− Metalloids tend
to be semiconductive
Pure Substances: Organization of the PT
• The elements in the far right column are the
noble gases
− They are unique in that they are generally
− All are gases at room temp
− Ne, Ar, Kr, and Xe are all used
in lighting
− Helium is used in party
balloons and weather