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Bonding, Compounds, Reactions
Periodic Table Review
What does the periodic
table tell me?
• Element symbol
• Atomic number: number of protons (and
usually electrons, neutrons)
• Atomic mass: the average of all the isotopes’
mass
• What type of element it is (metal, nonmetal, etc)
• What elements can bond together (valence #)
• In what ratio elements bond (oxidation #)
Reading the Periodic Table:
Elements
Atomic
number
16
Element
symbol
32.06
Atomic
mass
Types of Elements
• Metals: usually shiny, conductors,
malleable, ductile, solids at room
temperature. On left side of periodic table
• Non-metals: gas or brittle solid at room
temperature, insulators. On right side of
periodic table.
• Metalloids: have properties of both
metals and non-metals. Between metals
and non-metals.
Three types of Elements
Things to remember with
symbols
•
•
•
•
They are either one or two letters.
Only the first letter is capitalized!
Some symbols are based on the Latin name
Some of the newest symbols use three
letters until they are renamed (the atomic
number in Latin)
Periodic Table
Metalloids
Metals
Transition
Metals
Nonmetals
Noble Gas
Halogen
Types of Elements
• Noble Gas: Chemically stable. Has outer valence
level full. “Happy” AKA: Inert elements. Don’t bond
with others.
• Halogens: Are non-metals. Bond VERY easily. Have
7 electrons in outer shell.
• Non-metals: Do not easily conduct electricity or heat.
• Metalloids: Have traits of both metals and non-metals.
• Metals: Good conductor of heat and electricity, shiny,
ductile (pulled into a wire), and malleable (pounded
into flat sheets)
• Transition metals: Metals that can have two different
valence numbers. Is shown in the formula. Example:
Fe (II)
Periodic Table
Alkali
metals Alkaline Earth
metals
Transition metals
Chemical Bonds
• The forces that hold atoms or ions together
Word wizard: Ionic Bond
Your definition
Important Points
Bond that is formed by
the “stealing” of
electrons.
Examples
Ionic Bond
Sodium Chloride: NaCl
Sugar: C6H12O6
One atom is now + and one
is now -. This makes them
attract to each other. Most
are solid at room temp.
Non-Examples
Water: H2O
Diatomic molecules: Cl2,
H2, N2 (gasses)
Word wizard: Covalent Bond
Your definition
Important Points
Bond that is formed by
the “sharing” of
electrons.
A stronger bond than ionic.
Atoms can share more than
one electron. Most are
liquid or gas at room temp.
Covalent Bond
Examples
Non-Examples
Water: H2O
Sodium Chloride: NaCl
Diatomic molecules: Cl2,
H2, N2 (gasses)
Sugar: C6H12O6
Word wizard: Anion
Your definition
Important Points
An ion that has a
negative charge; has extra
electrons.
Examples
Anions have more
electrons than protons.
This makes them
negative overall.
anion
Non-Examples
Chlorine
Sodium
Oxygen
Potassium
Nitrogen
Magnesium
Non-metals
Metals
Word wizard: Cation
Your definition
Important Points
An ion that is positively
charged; has less
electrons
Cations lose electrons.
They have more protons
than electrons and are
positively charged.
Cation
Examples
Sodium
Potassium
Magnesium
Metals
Non-Examples
Chlorine
Oxygen
Nitrogen
Non-metals
Word wizard: Chemical Formula
Your definition
Important Points
A shorthand way of
writing compounds using
their symbols.
Examples
Large and small letters.
Shows what elements are
in a compound and how
many of each.
Chemical
formula
Non-Examples
H2O
Water
C6H12O6
Sugar
NaCl
Salt
Word wizard: Chemically Stable
Your defintion
Important Points
Elements that have the
outer electron shell full.
Will not typically bond
with other elements.
Also called “Noble
Likes to be ALONE!
Gases” or “Inert
Chemically
Elements”
Examples
Stable
Non-Examples
Helium
Krypton
Neon
Xenon
Argon
Radon
Gold
Sodium
Carbon
Nickel
Potassium Oxygen
Valence Numbers
Valence
1
2
3 4
5
6
7
8
Diatomic Molecules
• Covalent bond
between identical
atoms.
• Usually a gas
• Examples:
– H2 (hydrogen gas)
– O2(oxygen gas)
– N2(nitrogen gas)
• Nitrogen has 5
electrons in the
outer shell.
• It wants 8.
• Two nitrogen atoms
share three
electrons.
• BONDED!
Making Compounds
Let’s bond, shall we?
Valence Numbers
• Valence electrons: how many electrons are
in the outer shell.
• Chemically stable: elements having their
outer shell full. The noble gases are
chemically stable without bonding.
• To fill the outer shell, elements can share or
steal electrons (bond).
• To be “Happy” atoms typically want 8
electrons in the outer shell (ionic or
covalent bonds)
• Stealing electrons
• This makes one
negatively charged (it
has an extra electron that
it stole). The other is
now positively charged
(had an electron taken).
Opposites attract!
• Ionic bonds are weaker
than covalent.
• Compounds that are
solids at room
temperature are usually
from ionic bonds.
Ionic bonding
• From sharing
electrons
• Covalent bonds are
stronger than ionic
• Compounds that are
liquids or gas at room
temperature are
typically covalent
bonds.
• Diatomic: Some
elements will
covalently bond with
themselves!
Covalent Bonding
Common Household Compounds
Baking Soda: NaHC03
Carbon Monoxide: CO
Sand: SiO2
Ammonia: NH4
Carbon Dioxide: CO2
Salt: NaCl
Bleach: NaClO
Propane: C H
3 8
Vinegar:
HCH3O2
Water: H2O
Stomach Acid: HCl
Ionic Compound Naming
• Metal first then nonmetal
• Nonmetal gets –ide ending
Dihydrogen Monoxide
The dangers, uses and potential threats posed by this chemical, Dihydrogen
Monoxide, are widespread, and some feel, terrifying. Here is just a small taste of
what Dihydrogen Monoxide (DHMO) is:
Some call Dihydrogen Monoxide the "Invisible Killer"
In it’s gaseous form, DHMO can cause severe burns
Dihydrogen Monoxide is found in all cancerous tumors
Athletes use DIHYDROGEN MONOXIDE, or DHMO, to enhance
performance
Dihydrogen Monoxide has been found to cause failure in automotive breaks
Dihydrogen Monoxide is a major component of acid rain
Thousands die each year after inhaling dihydrogen monoxide
Dihydrogen Monoxide can be deadly
Visit DHMO.org to find out more
What’s in a name?
•
•
•
•
•
Mono = one
Di = two
Tri = three
Tetra = four
Penta = five
• Examples:
– Carbon Monoxide CO
– Carbon Dioxide CO2
– Dihydrogen Monoxide ??
H2O
Covalent Compound Naming
• If only one atom in first element the name
does not get a prefix
• The element farther to the right on the
periodic table is named second and ends in
-ide
Dot Diagrams
• What you need to know to make a dot
diagram:
• Chemical symbol
• valence number
• How to draw the dot diagram of an element:
1. Write the symbol
2. Find the valence number
3. Fill in dots
P
– two together (the S ones)
– one in other sides until you run out of room.
More Dot Diagrams
Li
F
Mg
Ge
Kr
Se
I’m still seeing dots!
Sr
As
Why is this one right?
He
Because Helium only has two electrons in the first place!
Oxidation numbers
+1
+2
+3 +/-4 -3 -2 -1
Making Compounds
• Criss-Cross Method:
– List the Metal first, non-metal second.
– Write the oxidation number above the symbol.
– Criss-cross the numbers. (a 1 does not need to
be written, drop the + or -)
– Final answer lists only the subscripts (numbers
below the line)
– If they are the same number, they cancel out
Example: Combine Hydrogen and Chlorine
+1
-1
H Cl
=
HCl
Now try these...
Hydrogen and Oxygen
+1
H O
-2
H2O
Magnesium and Nitrogen
Mg
+2
N
-3
Mg3N2
Writing Equations
• Remember the “criss
cross” method.
Example: Combine H and O
+1
-2
– Use the oxidation
number
– Don’t write in 1’s or
the charges
2
– Oxidation numbers
Example: Combine Fe (III) and O
of transition
elements are given
+3
-2
in a roman numeral.
– Put in “lowest
terms”
H O
H O
Fe
O
Fe2O3
Writing Equations: something new
• Monoatomic Ions:
– “normal”
– one element
– can get from the periodic table or roman numerals
– what you’ve been working with
– Example: H20
Example: Combine
• Polyatomic Ions:
– compounds that always work together.
– Always has more than one element
– Get the information off a chart
– Criss cross method still works.
– Keep these elements together!
Potassium and
Permanganate
K
+1
MnO4
KMnO4
-1
More Practice: Polyatomic Ions
Combine: Iron (II) and Nitrate
Fe
+2
NO3
-1
Fe(NO3)2
Combine: Calcium and Carbonate
Ca
+2
-2
CO3
CaCO3
Word wizard
Your definition
Important Points
The mixture can have
new properties. (lower
melt point, stronger,
etc.
Two or more metals
melted down and
mixed together.
Real example
Sterling silver, 14
karat gold, bronze,
brass
Alloy
Analogy/memory hook
Not ALL metals are
mixtures. (All = alloy)
Alloys are like allies
(mixed but not the same)
Word wizard
Your definition
Basic equation
Reaction where
substances are
combined to make
a new substance.
A + B
AB
Synthesis
Reaction
Real example
2Mg + O2
2MgO
Analogy/memory hook
Like two people going
out and becoming a
“couple”.
Dating is a “sin”
Word wizard
Your definition
Basic equation
One ingredient
“kicks out” the
other. Leaders
always stay leaders!
A + BC
AC + B
D + BC
BD + C
Single replacement
Reaction
Real example
Li + FeBr2
LiBr + Fe
Analogy/memory hook
Getting “dumped” for
someone else.
One ends up single
Word wizard
Your definition
Basic equation
Elements will change
partners in this type
of reaction. Leaders
are always leaders!
AB + CD
AD + CB
Double replacement
Real example
Reaction
AgNO3 + NaCl AgCl + NaNO3
Analogy/memory hook
Switching dates at
the prom.
Nobody gets left
alone!
Word wizard
Your definition
Basic equation
A substance is
broken down into
its “parts” in this
reaction
AB
A+ B
Decomposition
Reaction
Real example
2H2O
elec
H2 + O2
Analogy/memory hook
A couple breaking up.
Things “break down”
when they decompose.
Word wizard
Your definition
Basic equation
A reaction where
two of the
products are
water and carbon
dioxide
Real example
HCl + Na2CO3
A+B
CO2 + H20
Combustion
Reaction
CO2 + NaCl + H2O
Analogy/memory hook
Combustion = fire
Picture a fire with smoke
(CO2) and water(H20) to
put it out.
Word wizard
Your definition
Important Points
Chemical reaction
where heat is
ABSORBED.
Heat being
absorbed makes it
feel COLD.
Endothermic
Real example
Break and shake ice
pack. (Heat is
absorbed by ice
pack, but it feels
cold)
Reaction
Analogy/memory hook
Endo has a “d” in it.
Cold has a “d” in it.
Endothermic
reactions FEEL cold.
Word wizard
Your definition
Important Points
Chemical reaction
where heat is
released.
This reaction will
feel warm/hot.
Exothermic
Real example
“Hand warmers”
BenGay,
Thermocare hot
wraps
Reaction
Analogy/memory hook
“Exo” = “exit”
Heats EXITS an
exothermic reaction.
(it feels warm)
You can’t play “God”
• Law of Conservation of Mass says that we
can’t create or destroy mass!
• Example: the weight of a piece of paper
will be the same as the weight of the ash,
smoke, etc after you burn it!!
• In chemical reactions, you need to have the
same amount of atoms before and after the
reaction!
It’s a balancing act
Ag + H2S
Ag2S + H2
Ag
1
Ag
2
H
2
H
2
S
1
S
1
Not Balanced!
Conservation of
mass says we can’t
create or destroy
anything!!
It’s a balancing act
2 Ag + H2S
Ag
1 2
Ag
2
H
2
H
2
S
1
S
1
Ag2S + H2