Unit Learning Goal
 Attraction and repulsion between electric
charges at the atomic scale explain the
structure, properties, and transformations of
matter, as well as the classification of the
matter.
Valence Electrons
and the Octet Rule
Bonding
Ionic
Covalent
Metallic
Valence Electrons
 What are they?
▪ Outer Shell Electrons
 These electrons make all
bonds happen.
All atoms “want” to
obtain the electron
configuration of a noble
gas
 Usually this is 8 outer
shell electrons
Dots to indicate
the number of
electrons in the
outer shell
Na
Ca
O
N
F
Si

Achieve Noble Gas
 Give & Take of Electrons
▪ =Ionic Bond
 Sharing Electrons
▪ =Covalent Bond
Ionic Bonding

Ionic bonds occur because of a Transfer of
Electrons
These two atoms are NOT happy: How can we help
them out?
The atom with the extra electrons gives them to
the one who “wants” electrons
+2
-2
Note that after the transfer
of electrons the atoms acquire a charge: +2 and -2

The oxidation number of an element
indicates the number of electrons lost,
gained, or shared as a result of chemical
bonding. It is the charge of atoms after they
have their complete octet.



Ions are always attracted to each other due to
the attraction between opposite electrical
charges.
Positive and negative charged ions attract
each other till the total charge is ZERO.
1 Na+ + 1 Cl- = NaCl no charge
(balanced)

Definitions
 Salt
Ionic compounds are often referred to as salts.
 Crystal Lattice
▪ A repetitive arrangement of atoms in an ionic
compound
One Na for every one Cl



Formula is a ratio: NaCl does not mean one
Na connected to one Cl
It means Na1,000,000Cl1,000,000
So it looks like…
Property
Reason
High melting point
Due to strong bonds
Do not conduct
electricity when solid
Solids at room temp.
Electrons can’t move
Good conductors when
dissolved or liquid
Brittle and hard
Ions are free to move
Strong bonds
Strong bonds
Polyatomic Ions are ions that have more than one
atom. Often these ions can include nonmetal
atoms.
 Polyatomic ions are groups of atoms that act
together as one unit


Transition Metals are always cations just like
all metals.

Transition Metals often have more than one
possible charge. It is necessary to check for
possible charges when we make our ionic
compounds.

We must consider these ions as groups that
always travel together.
Iron II Oxide
` Iron III Oxide
THE NAME OF
IMPORTANT!
COMPOUNDS ARE VERY
Because they tell you what is in that compound!

The periodic table group numbers signify the
number of valence electrons members of that
group each have.

The valence electron number will indicate
whether or not that element/group will lose or
gain electrons, and how many
 Groups 1-3 and the transition elements lose electrons
to become positive ions
 Groups 5-7 gain electrons to become negative ions
 Group 4 and 8 do not readily form ions

Ionic compounds are formed between a metal
and a nonmetal
 Metals: groups 1, 2, 3, & the transition metals (short
rows)
 Nonmetals: primarily groups 5, 6, & 7

To name them: Cation + (Anion + ide)
 Cation: positive ion
 Anion: negative ion
 Na + Cl = Sodium Chloride

Compounds are by definition neutral. When
combining ions to form an ionic compound, the
overall charge of the compound must equal zero

Subscripts are used to indicate the number of
each element needed in order to have a neutral
compound

For example:
 Na + Cl = NaCl (+1, -1 equals zero)
 Mg + Br = MgBr2 (+2, -1, -1 equals zero)
When naming compounds with polyatomic ions,
use the name of the polyatomic ion with no –ide
suffix
 For example: K2S = Potassium sulfide while
K3PO4 = Potassium phosphate
 In the example above, the rules for determining
subscripts remains the same: the goal is for the
compound to be neutral (no electrical charge)
 K = +1 charge, PO4 = -3 charge and so I will need
three K+ ions to bond with one PO4 polyatomic
ion in order to reach an electrical charge of zero
(neutral


When naming a compound containing an
element that can form more than one type of
ion, a Roman numeral is used to indicate the
charge of that ion in that particular
compound

Copper (II) Oxide: Copper has a +2 charge,
and therefore the formula will be CuO
Copper (I) Oxide: Copper has a +1 charge and
therefore the formula will be Cu2O


When nonmetals combine, the naming system is
different.
 Because you cannot necessarily use the charge to
indicate the quantities of each atom in the compound,
the name must indicate the amounts using standard
prefixes: mono, di, tri, tetra, penta, hexa, hepta, octa,
nona, and deca

The only time a prefix is not used is for the first
element of the name when there is only one of
that element in the compound.
 CO carbon monoxide
 N2O4 dinitrogen tetraoxide