Chemical Bonds
Chapter 6
Compare – Eyes on Chemistry
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Epsom Salts
Rock Salt
Sucrose
One more…
• WHAT DO YOU NOTICE ABOUT THEIR
STRUCTURE?
Valence Electrons and Lewis Dot
Structure (AKA Electron Dot)
• Remember: Octet Rule? Valence Electrons?
• How many valence electrons in…
• Example Sulfur (A#16)
• Your turn 1-20 – count off!
Stable Electron Configurations
Stable Electron Configurations
Stable Electron Configurations
Stable Electron Configurations
Stable Electron Configurations
Stable Electron Configurations
Stable Electron Configurations
Stable Electron Configurations
Stable Electron Configurations
Ionic Bonding
• Relationships are weaker when you
take/borrow/steal…
• It means someone had to give/lend/be
robbed
• Where the analogy breaks down…
– Who is left feeling more negative?
– Who is more positive?
• What happens when negatives and positive
are near each other?
Ca+ion vs. Anion
NaCl
Oxidation #
- Can you predict which elements will form ionic bonds with which?
- Which groups with which groups?
- Metals with Metals? Metals with Non-metals?
MgCl2
Covalent Bonding (6.2)
• Relationships are stronger when you share
• Bond Strength -- Covalently bond > Ionic bonds
• One pair of shared electrons?
• Two pairs of shared electrons?
• Three pairs of shared electrons ?
Three fish
Molecules = ? - Define it!
Lewis Dot of Covalent Bonds –
• Dr. B - Practice
Polar Covalent Bond
Share…but not equally
Results in partial charges = polarity
EXAMPLE: Water
Nonpolar Covalent Bonds
Name
Formula
Carbon dioxide (CO2)
Formula: CH4
Shape Matters!
- Geometry
- Symmetry
Nonpolar Covalent Bonds
Formula: CH4
Name: Methane
Carbon dioxide (CO2)
Shape Matters!
- Geometry
- Symmetry
Molecular Compound – bonded molecules
• Forces of attraction that hold molecules
together in a liquid or solid
- Stronger in polar or nonpolar molecules?
Ex. Hydrogen bonds
(Van der Waals Forces)
Nomenclature -- How do you name or talk
about compounds and molecules?
– Formulas - describes the ratio of ions in the
compound
– Name – words to describe/identify it.
Binary compound = only two elements
Metal + Nonmetal = ?
Nonmetal + Nonmetal = ?
Metal + Metal = ?
Talking Ionically…
Pattern/Rules for Name…
name of cation + name of anion + “-ide”
When writing an ionic formula between a metal and a nonmetal follow these
5 steps:
1.
2.
3.
4.
5.
Write the symbols for the metal and the nonmetal.
Write the valences as superscripts above each symbol.
Drop the + and - sign.
Crisscross the valences so they become the subscript for the other element.
Reduce subscripts whenever possible. Only when both are divisible by a number greater
than one.
Show me how…
Practice
Using a periodic table try these then check your answers.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
sodium and phosphorus
magnesium and fluorine
aluminum and sulfur
calcium and nitrogen
barium and iodine
potassium and bromine
aluminum and phosphorus
strontium and oxygen
magnesium and nitrogen
cesium and phosphorus
• Check your answers
When the metal (ca+ion) is a
Transition Metal…
• More than one type of ions possible
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•
A Roman numeral in parentheses, following the name of the element, is used
for elements that can form more than one positive ion. This is usually seen with
metals.
You can use a chart to see the possible valences for the elements.
• Fe2+ Iron (II) Cu+ Copper (I)
Fe3+ Iron (III) Cu2+ Copper (II)
• Use Roman Numerals to indicate the charge
– Ex. Copper (II) ion + Chlorine 
Cu2+ + __Cl-  CuCl?
Cu+ Cuprous
Cu2+ Cupric
Ionic Compounds - Naming of anions
-ide
The -ide ending is added to the name of a monoatomic ion of
an element.
H- Hydride
F- Fluoride
O2- Oxide
S2- Sulfide
N3- Nitride
P3- Phosphide
-ite and -ate
Some polyatomic anions contain oxygen. When an element
forms two oxygen containing anions they are named with
different suffixes/endings:
-ite = the one with less oxygen
-ate = the one with more oxygen
Examples:
NO2- Nitrite
NO3- Nitrate
SO32- Sulfite
SO42- Sulfate
Practice
Using a periodic table try these then check your answers.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
iron(III) and phosphorus
copper(II) and fluorine
silver(I) and sulfur
manganese(II) and nitrogen
lead(IV) and iodine
copper(II) and bromine
gold(II) and phosphorus
lead(IV) and oxygen
silver(I) and nitrogen
copper(II) chloride
Check your answers
Compounds containing
POLYATOMIC ATOMS
Polyatomic Ion: covalently bonded group of atoms that has a positive or negative charge and acts as a unit
When you write formulas for compounds containing a polyatomic ion:
1. Write the symbols for the metal and the polyatomic ion.*
2. Write the valences as superscripts above each.
3. Drop the + and - sign.
4. Crisscross the valences so they become the subscript for the other element.
5. If you have more than one of the polyatomic ion, you must encase it in parenthesis
and place the subscript outside.
6. You can only reduce a subscript outside the parenthesis of a polyatomic ion - you
cannot change the formula the polyatomic ion.
*In the case of ammonium (the only polyatomic cation) you would write it first and then
the anion
Let me show you…
Let me show you…
Practice…
Try these using a periodic table an a list of polyatomic ions.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
aluminum and sulfate
ammonium and sulfur
barium and hydroxide
magnesium and phosphate
lead(IV) and sulfite
strontium and carbonate
zinc(II) and phosphate
ammonium and oxygen
calcium and nitrate
tungsten(II) and sulfate
Check Answers
COVALENT FORMULAS: TWO NONMETALS
Because covalent compounds share electrons they can share in different ways and can
form many compounds between the same two elements.
IMPORTANT: You never crisscross valences to determine covalent (two nonmetals)
formulas.
So just how do you write the formulas? Prefixes - that's how.
Here are six covalent compounds that form between nitrogen and oxygen:
nitrogen monoxide = NO
nitrogen dioxide = NO2
dinitrogen oxide = N2O
dinitrogen trioxide = N2O5
dinitrogen tetroxide = N2O4
dinitrogen pentoxide = N2O5
Practice – Name these
Just look at the name and you have the formula for a covalent
compound.
Go ahead and try these:
1.
2.
3.
4.
5.
sulfur dioxide
dihydrogen oxide
phosphorus pentafluoride
carbon tetrachloride
aluminum trichloride
Check your answers
MORE Practice/Review
• Quia.com
6.4 Metallic Bonds
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How they form….common pool of electrons
Metallic Lattice structure
How they give metal its strength…
Alloys…combined properties
POLYATOMIC ION: A covalently boned group of atoms that has a positive
or negative charge and acts as a unit … ex. Iron (III) Oxide Fe(OH)3
Electronegativity
HOW DO THE ELECTRON CONFIGURATIONS CHANGE?
ACROSS THE SAME PERIOD?
DOWN THE SAME GROUP?
HOW DOES THE RADIUS OF AN ATOM CHANGE WHEN IT BECOMES AN ION?
How does the radius change…
When it becomes a cation?
When it becomes an anion?
Radius of the atom
Charge of the ion (# electrons lost/gained)
Radius of an ion of the atom
Predict the radius change and
# of valence electrons for
Francium (Fr)
Not learned in this class….but interesting:
hypo- and perIn the case where there is a series of four oxyanions, the hypo- and per- prefixes are used in
conjunction with the -ite and -ate suffixes. The hypo- and per- prefixes indicate less oxygen
and more oxygen, respectively.
ClO- Hypochlorite
ClO2- Chlorite
ClO3- Chlorate
ClO4- Perchlorate
bi- and di- hydrogen
Polyatomic anions sometimes gain one or more H+ ions to form anions of a lower charge.
These ions are named by adding the word hydrogen or dihydrogen in front of the name of
the anion. It is still common to see and use the older naming convention in which the
prefix bi-is used to indicate the addition of a single hydrogen ion.HCO3- Hydrogen carbonate
or bicarbonate
HSO4- Hydrogen sulfate or bisulfate
H2PO4- Dihydrogen phosphate