Exam Review,
Fall 2014
Significant Figures
Use with
Measurements!
1. Leading 0’s NEVER count
2. Trailing 0’s count ONLY if
there is a decimal
3. Trapped 0’s ALWAYS count
Do not use SFs with FACTS
or Counts!
Very important!
Use the measurements
in the ORIGINAL problem to figure out
how many SF’s you need.
Scientific Notation
•
With Scientific Notation, you always have
one, and only
one
, digit to the left of the decimal place
•
When written in scientific notation, numbers
greater than 10 have positive exponents
•
Numbers between 1 and 10 are not written in
scientific notation
•
When written in scientific notation, numbers less
than 1 have negative exponents
Scientific Notation continued..
Multiplication
To multiply numbers written in SN, multiply the
coefficients and add the exponents
Division
To divide, divide the coefficients, and subtract the
exponent in the denominator from the exponent on the
numerator
Addition and Subtraction
Before you can add or subtract SNs, you must make the
exponents the same. It does not matter which exponent
you change.
Move to right or to left?
An easy way to remember if you should move your
decimal to the left or to the right is that if you
make your original coefficient smaller, your
exponent will become bigger, and if you make your
coefficient bigger, your exponent will become
smaller.
Ex: if you start with 5.68 x 10
4, and you need to
make it .00568 to add it or subtract it, you have
made the number smaller, so your exponent will
be bigger--.00568 x 10
7(which equals 5.68 x 10
4)
Lab Safety
•
Confirming Test?
–
The proof that a substance
is present
•
Qualitative Test?
–
How you tell if something
is, or is not, present e.g.
color change
•
Quantitative Test?
–
Identifies how much of
something there is
Evidence of a Chemical Reaction
o
Color Change
o
Temperature
Change
o
Gas Release
o
Disintegration, or
formation of a new
substance
o
Precipitate
o
Odor Change
ATOMS!
Atoms: building blocks of matter (smallest
particle possessing the properties of an
element)
Elements are composed of only one type
of atom
•
Matter: anything
that occupies space
and has mass
•
Density: Mass
•
Compound—2 or more elements
combined in fixed proportions
•
Molecule—the smallest particle of a
substance made up of 2 or more atoms
retaining all properties of the substance
Periodic Table
Know the names =
symbols of the 1
st
36
elements!
Plus other common
ones: Hg, Au, Ag, Pb,
Xe, Rn, and Sn
Atomic Number vs.
Mass Number vs. Atomic Mass
Atomic Number
•Always the number of protons the element has
•Uniquely identifies the element
•Always a whole number
Mass Number
•
Number of Protons and Neutrons (found in nucleus)…
always a whole number
Atomic Mass
(AMU for a single atom or
compound---grams for a mole)
•
Mass of protons, electrons, and neutrons
Isotopes are different
types of atoms of the
same element that
have a different
number of neutrons
Identify it this way:
5
He,
6
He, etc.
Ex.:
7
He would have 2
protons and 5
neutrons
Chemical Equation
Reactants Products
Chemical Reaction
Electrical Nature of Matter
•
Protons +
•
Electrons
•
Physical Properties: color, luster,
boiling/melting/freezing point, density, odor
–
Properties that can be determined without
changing the chemistry of the material
•
Physical Change: Material remains the same
although the form seems to have changed
(copper coin/copper wire)
•
Chemical Properties:
Reactivity, pH, types of
bonds that will form,
oxidation states,
combustibility,
•
Chemical Change:
–
Formation of gas or solid,
permanent color change,
temperature change,
Ions and Ionic Compounds
Atoms gain/lose electrons to become ions
•
Electrically charged atoms or groups of atoms
–
Cation?
–
Anion?
Polyatomic Ions: NO
3-, HCO
3-, PO
43-Sodium Ion: 11 protons (11 + charge)
+ 10 electrons (10 – charge)
A compound must be
electrically neutral! Ionic
Bonding…
If you have Na
+
+ SO
4
2-
, you would
have NaSO
4
-To make it electrically neutral, you
must have 2 sodiums! Na
2
SO
4
Periodic Table
Organizes metals, non-metals
and metalloids
•
Are there more metals or non-metals?
•
Properties of metals?
•
Properties of non-metals?
•
Metalloids?
Organization of the Table
•
Groups/Families
•
Periods
•
Atomic Number
•
Atomic Weight
•
Oxidation number
(Ionic Charge)
•
Valence electrons
SI Numbers!
Quantity Unit Abbreviation
Mass kilogram kg
Length meter m
Time second s
Temperature kelvin K
Amount of Substance mole mol Electrical Current ampere A Luminous Intensity candela cd
Metric Prefixes
Prefix Abbreviation Meaning Example
mega- M 106 1 megabyte = 1,000,000 bytes
kilo- k 103 1 kilogram = 1,000 g
deci- d 10-1 1 deciliter = 0.1 liter
centi- c 10-2 1 centimeter = 0.01 meter
milli- m 10-3 1 milliampere = 0.001 A
Know numerical prefixes
1 = mono-
6 =
hexa-2 = di-
7 =
hepta-3= tri-
8 =
octo-4 = tetra-
9 =
deca-Activity Series
Some Metals
are more
reactive than
others
To reduce metal ions
and get free metal out of ores:
•
Pyrometallurgy
•
Hydrometallurgy
The same quantity can be expressed in many ways.
1 dollar =
4 quarters =
10 dimes =
20 nickels =
100 pennies
Different ways to express the same amount
Dimensional Analysis:
Whenever two
measurements are equal, a
ratio of these two
measurements will equal 1
100 cm = 1 m = 1
1 m
100 cm
Which one?
1 kg or 1,000 g
1,000 g 1 kg
Choose the one that allows you to cancel
the units!
2,678 g x 1 kg = 2.678 kg
1,000 g
Percent Composition
Grams of element x 100 % = % composition of
Grams of compound element
An 8.2 gram piece of Ca combines completely
with 5.4 g of Oxygen to form a compound
(CaO). What is the % composition?
% Composition refers to
all
the components of
the molecule!
Conserving Matter
•
Law of
Conservation
of
Matter---matter is
neither
created nor
destroyed
Atom Inventories/Balancing Equations
•
Since matter is neither created nor
destroyed, atoms can always be
accounted for
2H
2
+ O
2
→ 2 H
2
O
The atoms on the reactant side must be
the same as the atoms on the product
side
Balancing Equations:
Coefficients are used to balance
equations—they reflect the
relative number of units of
each substance involved in
the reaction
Subscripts indicate the number
of atoms present in a
Rules for Balancing Equations
Determine the correct formulas for all reactants
and products
Put the reactants on the left side of the yields
sign (→) put the products on the right
C
2
H
5
OH + O
2
→ CO
2
+ H
2
O
1) Set the equation up algebraically:
2) Do an atom inventory:
a
C
2
H
5
OH +
b
O
2
→
c
CO
2
+
d
H
2
O
C: 2
a
=
c
H: 6
a
= 2
d
3) Make one coefficient = 1; solve for
the other coefficients:
a
= 1
C: 2(
a
) =
c
, 2(1) =
c
,
2 =
c
H: 6(
a
) = 2(
d
), 6(1) = 2
d
, 6 = 2
d
,
3 = d
O:
1
a
+ 2
b
= 2
c
+ 1
d
, 1(1) + 2
b
= 2(2) + 1(3)
Solve for b: 1 + 2
b
= 7, 2
b
= 6,
b = 3
a
C
2
H
5
OH +
b
O
2
→
c
CO
2
+
d
H
2
O
Zn:
a
(1) =
c
(1) →
a
=
c
H:
b
(1) =
d
(2) →
b
= 2
d
Cl:
b
(1) =
c
(2) →
b
= 2
c
3) Make one coefficient = 1; solve for the other
coefficients
a = 1
. Since a = c,
c = 1
.
b = 2c --- b = 2 (1) ---
b = 2
4) Do another atom inventory
C
2
H
5
OH +
3
O
2
→
2
CO
2
+
3
H
2
O
C: 2 → 2
H: 6 → 6
0: 7 → 7
Molecules,
Compounds
•
Molecule: electrically neutral -- group of atoms
(can be same element) that act as a unit
Compound: Molecule with at least 2 different
elements
•
Molecular/Covalent compound: electrically
neutral-- composed of 2 or more atoms,
non-metals
•
Ionic Compound: electrically neutral—
usually
Ionic Bonding
•
Occurs between a metal and a non-metal
•
The result of anions and cations being
attracted to one another—will form an
electrically neutral compound
Naming Rules
•
Cation is named first then anion
•
Cation retains its name
•
Anion ends in “-ide”
–
unless it is a polyatomic ion
Some Ionic Compounds…..
