Transcript Chapter 7 Elements Compounds and Mixturesx

Pure Substance
A pure substance is a substance in
which all the particles (atoms) are of
one kind Gold (Au), Silver (Ag),
Chlorine (Cl), Sodium (Na).
In other words the atoms are all the
same type which is what gives it its
physical & chemical characteristics.
Element
Elements are pure substances that cannot
be separated into simpler substances by
physical or chemical means. All the
atoms of an element are of one kind.
Elements have physical & chemical
properties that help identify them
because they do not change based on
how much of the element there is.
Periodic Table
• The modern periodic table has
space for 118 elements. Only
4 of the 118 have not been
officially named. When the
th
119 element is discovered
the periodic table will have
th
add its 8 period or row.
Metals
Generally shiny, solids at
room temperature except for
(Mercury which is a liquid
(Hg), good conductors of heat
and electricity, malleable,
and ductile. Left of zigzag line
Metals
Common Examples: Gold,
Aluminum, Copper, Zinc, Nickel,
Lead, Sodium, Magnesium,
Potassium, Iron, Calcium
Non-metals
Generally dull, brittle, not
ductile, poor conductors of
heat and electricity. 11 are
gases, 1 liquid (Br), and 6 are
solid. Right of zigzag line.
Non-Metals
Common Examples: Sulfur,
Carbon, Phosphorus, Bromine,
Oxygen, Iodine, Hydrogen,
Helium. Chlorine, Fluorine, and
Nitrogen.
Metalloids
Semi-conductors that have
similar properties of Metals and
Non-Metals. Some are shiny,
some are dull. Some are
somewhat malleable, some are
brittle. Some conduct heat and
electricity well, some do not.
Located along the zigzag line.
Metalloids
The most used metalloid is
silicon and it is used in
computer chips. Germanium
and arsenic are also used in
trace amounts in computer
chips.
Metalloids
Examples are Boron,
Silicon, Germanium,
Arsenic, Antimony,
Tellurium, and sometimes
Astatine.
Compounds
•Compounds cannot be
broken down by physical
means. They must be
broken down chemically
Compound Properties
The properties of a
compound are usually
different versus the reactant
elements. Most reactions
produce compounds with
unique properties.
Example
Carbon Dioxide CO2 -78.5°C Boiling point
solid Carbon 4827°C Boiling point
gas Oxygen -183°C Boiling point
Water H2O
100°C Boiling point
gas Oxygen -183°C Boiling point
gas Hydrogen -253°C Boiling point
Sodium Chloride NaCl 1413°C Boiling point
Sodium 889°C Boiling point
Chlorine -34°C Boiling point
Compounds you need
to know for the EOG
•Carbon dioxide - CO2
•Water - H2O
•Salt - NaCl
Specific Ratio
Compounds do not
just join together in
random fashion but
by specific ratio,
C6H12O6, NaCl, H2O
Breaking Down Compounds
Compounds are broken
down ONLY through a
chemical change. Can be
accomplished by applying
heat or an electric current.
Compounds in Nature
Proteins are compounds found in all
living things. Proteins are created
from long chains of amino acids.
Photosynthesis uses the compound
carbon dioxide & water & sunlight
to make the compounds called
carbohydrates (glucose).
Photosynthesis
6CO2 + 6H2O + sunlight energy =
C6H12O6 + 6O2
Cellular Respiration
C6H12O6 + 6O2 = 6CO2 +
6H2O + ATP (energy)
Water: A Unique Compound
Water- no living creature
can live without odorless
and tasteless water. It is
the most important
compound on Earth.
Water Properties
1.0 gm/ml density, expands when it
freezes(very important in rock cycle)
Can exist in solid, liquid, and gas at
standard atmospheric pressure.
High specific heat which helps
regulate Earth’s temperature
through the ocean absorbing heat.
Is polar in structure.
Universal Solvent
Water is considered the
universal solvent because
so many substances
dissolve in water. Water is
polar in its structure and
charge. “Sticks to itself”.
Cohesion vs Adhesion
Cohesion is the force that holds
molecules of a single substance
together. Water forms drops because
of cohesion. Example: water to water.
Adhesion is the force that holds
molecules of different substances
together. Example: water to towels.
Definitions
Solvent- a substance in which
something dissolves.
Solute- a substance dissolved by a
solvent.
Dissolved- goes into solution.
Example: Koolaid granular material is
the solute and the water is the solvent,
salt is solute and water is the solvent in
salt water.
Definitions
Dilute- small amount of
solute vs solvent
Concentrated- large
amount of solute vs
solvent.
Mixture
Any combination of two or
more substances that are not
chemically combine. A
mixture is formed if the
substances do not react to
form a compound.
Mixtures may be
Homogenous- uniformly
distributed particles, Kool-Aid in
water, coffee, tea, coke
Heterogeneous- unevenly
distributed particles, ingredients
on pizza, toss salad, cement mix,
rock/sand mix in the coke bottle.
Separating Mixtures
Can separate by physical
means:
Distillation, Filtering, or by
spinning in a Centrifuge.
Distillation
Separating by the different boiling
points of the components.
Examples: crude oil into gasoline,
kerosene, jet fuel, and asphalt.
Alcohol from fermented material
and fresh water from salt water.
Centrifuge
Spinning in a circle causing the
most dense material to settle
to the bottom. Separation
blood platelets from plasma,
separating different
components of atomic
particles (Iraq).
Centrifuge separates blood platelets
Mixtures
Mixtures do not have
definite ratio ( 1:1, 2:5, etc)
of components. The
components can vary in
any proportion.
Mixtures
1- No change in the original
properties of the components.
2- Separated by physical means.
3-Formed by using any ratio of
components.
Elements
• Elements are pure
substances that cannot be
separated into simpler
substances by physical or
chemical means.
Three Major Element Types
Metals
Non-Metals
Metalloids
Compounds
A compound is a pure
substance of TWO or MORE
elements that are chemically
combined (Bonded together).
The smallest part of a
compound is a molecule.
Compounds
1-Made of elements.
2-Change in the original
properties.
3-Separated by chemical means.
4-Formed using a set ratio of
components.
Mixture
A mixture is two or more elements or
compounds that are not chemically combined.
Does not react to form a compound. Example:
pizza is cheese, mushrooms, mushrooms,
Canadian bacon, Canadian bacon, tomato
sauce, and crust. You can pick out the
individual components of a mixture. Each item
in the mixture keeps it’s identity. Example:
Toss Salad is lettuce, cheese, tomato, dressing,
crust, and pickles.
Water
Carbon Dioxide
Sodium Chloride
Solutions
Particles are evenly distributed
throughout. Same appearance
and properties throughout the
mixture. Particles in a solution
are so small they never settle
out and cannot be separated by
filtering.
Solutions
Solvent/Solvent
Solute is the substance that is dissolved.
Solvent is the substance solute is dissolved
in.
When two liquids or two gases are
combined into a solution the substance with
the greater amount is the solvent. Example:
air (oxygen in nitrogen) or antifreeze
(alcohol in water) or brass (zinc in copper).
Solute/Solvent
Solutions may be
Solid in liquid (salt in H2O)
Liquid in liquid (antifreeze)
Gas in gas (Air O in N)
Gas in liquid (soda CO2 in
H2O)
Solid in solid (Brass=Cu in Zn)
Alloys
Alloys are made by dissolving
metals in metals. Our coins are
generally alloys; penny is copper
and zinc as we saw in the penny
lab.
Steel is carbon and other elements
dissolved in iron. Our coin the
nickel is copper and nickel.
Concentration
Is expressed as grams
solute/milliliter of solvent.
Dilute is less solute per unit of
solvent.
Concentrated is more solute per
unit of solvent.
35 grams salt in 175 ml of water
what is the concentration?
55 grams sugar in 500 ml of
water what is the concentration?
36 grams sugar in 144 ml of
water what is the concentration?
Which is the most concentrated
and which is the most dilute?
Solubility
Is the ability of solute to dissolve in
solvent at a certain temperature and
pressure.
Most solids are more soluble in liquid
as the temperature goes up (the solute
particles are further apart).
Most gases are less soluble in liquid as
temperature goes up (the gas more
easily escapes from the liquid).
Solubility
Ways to increase solubility are:
Mix or stir (get particles
moving not clumped together)
Heat (increase the particles
average kinetic energy)
Crush ( increase surface area)
Suspension
A mixture of particles dispersed in a
liquid or a gas but large enough
they will eventually settle out. Can
separate by passing through a filter.
Examples: Snow globe, Italian
Dressing, dirt particles in a
container of water.
Suspension
Colloid
A mixture that the particles sizes are
between a solution and a
suspension. Particles are dispersed
throughout but are not heavy
enough to settle out. Cannot be
separated by filtering. Examples:
milk, jello, stick deodorant, whip
cream, butter.
Colloid
Diatomic Elements
Are molecules of two
atoms of the same
element. Elements found
is nature as diatomic are,
H2, O2, N2, F2, Cl2, Cl2, and
I2.