ANYTHING WITH MASS AND VOLUME
Elements
Draw this chart!,
leave space to
define the terms
Pure
Substances
Compounds
Matter
Homogeneous
Mixtures
Heterogeneous
Pure Substances vs.
Mixtures
• A pure substance is made of only one
kind of material and has definite
properties.
• Matter that consists of two or more
substances mixed together but not
chemically combined is called a mixture.
Pure Substances:
• Elements are the simplest pure
substance.
– Examples: hydrogen, carbon, and
oxygen.
• The smallest particle of an element
that has the properties of that
element is called an atom.
Pure substances:
Compounds are pure substances that
are made of more than one element
bound together.
– Examples: water (H2O), and carbon
dioxide.
A molecule is formed when two or more
atoms chemically combine.
Example: water (H2O), O2
MIXTURES
Heterogeneous vs. Homogeneous
Homogeneous matter (solutions): matter
that has identical properties throughout.
Examples: salt water, gravy, whipped cream
Heterogeneous matter: matter that has parts
with different properties.
Examples: granite, soil, potpourri, cookies
LIQUID MIXTURES
Miscible vs. Immiscible
• Miscible Mixture: liquids that mix evenly,
forming a homogeneous solution.
Example: Soda mixed with Koolaid
• Immiscible Mixture: liquids that DO NOT
mix evenly, forming a heterogeneous
mixture. Example: Oil mixed with Water
EXAMPLES
• What type of matter are each of
the following… ?
SAND
SAND
Heterogeneous mixture
Salt (NaCl)
Salt (NaCl)
Pure Substance: COMPOUND
Air
Air
• Homogeneous mixture of:
Many gases make up mixture,
but it looks like it is all one gas.
Nitrogen, N2 78.08%
Oxygen, O2 20.95%
Argon, Ar 0.93%
Carbon dioxide, CO2 0.033%
Neon, Ne 0.0018%
Helium, He 0.00052%
Methane, CH4 0.0002%
Krypton, Kr 0.00011%
Nitrogen(I) oxide, N2O
0.00005%
Hydrogen, H2 0.00005%
Xenon, Xe 0.0000087%
Ozone, O3 0.000001%
Gold
Gold
Pure Substance:
ELEMENT: Au
Bronze
Bronze
Homogeneous
mixture of
copper and tin
(alloy: mixture
of metals)
Salad Dressing:
Salad Dressing:
Heterogeneous Mixture
Conservation
• Law of Conservation of Mass:
Mass cannot be created or destroyed.
• Law of Conservation of Energy:
Energy cannot be created or
destroyed; it may only change from
one form to another.
Matter and Energy
MUST be conserved
is the LAW!
Virtually everything is made up of atoms.
From the very large...
To the very small...
We are all made of atoms…and only
atoms.
This includes you
and me! Giggitty,
Giggitty, Goo!
Currently we
have about 117
kinds of atoms. In
the natural world
there exists 92
different kinds of
atoms.
The others have
been artificially
produced in
laboratories.
The Elements Song
We call each kind of atom an element,
and give it a specific name and symbol.
Copper
Gold
Cu
Au
Periodic Table
Abundance of
the elements, by
weight
The Earth’s interior is
rich in iron
Sand is made of
Silicon & Oxygen
The ocean
waters are made
of oxygen &
hydrogen
Atoms are made up of protons,
neutrons, and Of
electrons.
course real atoms
don’t look anything like
this you imbecile!
Protons and neutrons are found in
the nucleus of atoms -- roughly
at the center
Electrons
travel around
the nucleus.
Different kinds of atoms, or elements, are
different because they have different numbers of
protons.
It would be sweet if atoms
really were this huge!
We list the elements by
their atomic numbers the number of protons
they have.
Hydrogen, number 1
Helium, number 2
In several cases the atomic weights are in parentheses. This indicates that these elements have no stable isotopes; that is, they are radioactive. The value
enclosed in parentheses and used for the atomic weight is the atomic mass number of the most stable known isotope, as indicated by the longest half-life.
Physical Properties
• Physical properties: characteristics that
can be observed without changing the
identity of the substance.
• Examples:
–
–
–
–
–
–
mass
volume
color
shape
texture
density
Physical Changes
• Physical change: a change in the physical
form or properties of a substance that
occurs without a change in composition.
• Examples:
–
–
–
–
melting
freezing
grinding
dissolving
Chemical Properties
• Chemical property: describes a
substance’s ability to change into a
different substance.
• Examples:
– flammability
– reactivity
Chemical Changes
• Chemical change: occurs when a
substance changes composition by
forming one or more new
substances. (bonds are broken
and bonds are formed)
• Example:
– HCl + NaOH  NaCl + H2O
Indications of a Chemical Change…
Heat in Endothermic (feels cold)
Heat out Exothermic (feels hot)
Gas is given off (fizzing or bubbles)
Color Change
New Substance is Formed
Evaporation is a
physical change
Breaking is a physical
change.
Boiling is a change of
state, and therefore a
physical change!
Rusting is a Chemical
Change
Burning is a Chemical Change
Kinetic Theory
• All matter is made of atoms and
molecules that act like tiny particles.
• These tiny particles are always in
motion. The higher the temp., the
faster the particles move.
• At the same temp., more massive
(heavier) particles move slower than less
massive (lighter) particles. (inertia)
SOLIDS
• Definite shape?
• YES
• Definite volume?
• YES
• Molecules in a solid are tightly packed and
constantly vibrating.
Eureka: Molecules in Solids
LIQUIDS
• Definite shape?
• NO
• Definite volume?
• YES
• Some liquids flow more easily than others.
The resistance of a liquid to flow is called
viscosity.
– Honey has a high viscosity compared to water.
Eureka: Molecules in Liquids
GASES
• Definite shape?
• NO
• Definite volume?
• NO
• The particles in a gas are spread very far
apart, but can be compressed by pumping
them into a restricted volume.
Eureka: Molecules in Gases
Phase Changes (Changes of State)
• Changes in phase are examples of physical
changes.
•
•
•
•
•
•
Melting: solid  liquid
Freezing: liquid  solid
Vaporization: liquid  gas
Condensation: gas  liquid
Sublimation: solid  gas
Deposition: gas  solid
Changes of State
GAS
Vaporization
Sublimation
Condensation
Deposition
Melting
LIQUID
Melting
Freezing
SOLID
Energy Transfers
• ENERGY is the ability to change or move
matter.
• Energy is ABSORBED when substances
melt or evaporate.
– NOTE: our bodies cool down when our sweat
evaporates.
• Energy is RELEASED when substances
freeze or condense.
Melting
• The change of state from solid to liquid.
• Energy (heat) is absorbed by the
substance that is melting.
Freezing
• The change of state from liquid to solid.
Opposite of melting.
• Energy (heat) is released by the
substance undergoing freezing.
Evaporation
• The change of state at the surface of a liquid as it passes to a vapor.
This results from the random motion of molecules that occasionally
escape from the liquid surface.
– Energy (heat) is absorbed by the liquid
– Can happen at any temperature
Condensation
• The change of state from gas to liquid. The opposite of
evaporation.
– Energy (heat) is released by the gas to become a liquid.
Boiling
• Change from state from a liquid to a gas.
• Occurs throughout the liquid.
– boiling point/temperature is determined by pressure
– Energy (heat) is absorbed by the liquid for it to boil
and produce gas.
*Boiling & freezing points depend on the pressure.
Water at normal pressure (1 atm):
• For water at normal (every day) pressures:
• Melting/freezing point:
0 oC (32oF)
• Condensing/boiling point:
100 oC (212oF)
100°C
0°C
*Boiling & freezing points depend on the pressure.
Change the pressure  Change
the Boiling Point