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PART II
LET’SFIRSTREVIEWIONICBONDING
In an IONIC bond,electrons are lost or gained,resulting in the formation of IONS
in ionic compounds.
FK
FK
FK
FK
FK
FK
FK
FK+ _
FK+ _
The compound potassium fluorideconsists of potassium (K+) ions
and fluoride (F-) ions
FK+ _
The ionic bond is the attractionbetween the positive K+ ion
and the negative F- ion
An ionic bond is a metal and nonmetal
Sowhatarecovalentbonds?
In covalent bonding,atoms still want to achievea noble gas configuration(the octet rule).
In covalent bonding,atoms still want to achievea noble gas configuration(the octet rule).
But rather than losing or gainingelectrons,atoms now share an electron pair.
In covalent bonding,atoms still want to achievea noble gas configuration(the octet rule).
But rather than losing or gainingelectrons,atoms now share an electron pair.
The shared electron pairis called a bonding pair
In covalent bonding,atoms still want to achievea noble gas configuration(the octet rule).
But rather than losing or gainingelectrons,atoms now share an electron pair.
The shared electron pairis called a bonding pair
A covalent bond is between a nonmetal and a nonmetal
Cl2
Chlorineforms
acovalent
bondwithitself
ClClHowwilltwochlorineatomsreact?
ClClEach chlorine atom wants to gain one electron to achieve an octet
ClClNeither atom will give up an electron –chlorine is highly electronegative.
What’s the solution – what can theydo to achieve an octet?
ClCl
Cl Cl
Cl Cl
Cl Cl
Cl Cloctet
Cl Cloctet
Cl ClThe octet is achieved byeach atom sharing theelectron pair in the middle
Cl ClThe octet is achieved byeach atom sharing theelectron pair in the middle
Cl ClThis is the bonding pair
Cl ClIt is a single bonding pair
Cl ClIt is called a SINGLE BOND
Cl ClSingle bonds are abbreviated
with a dash
Cl ClThis is the chlorine molecule,
Cl2
These are atoms that are never, never, never found alone in nature.
H2, N2, O2, F2, Cl2, Br2, I2
There are 7 diatomic molecules
Start with 7 on the periodic table
That would be Nitrogen (this is one of the diatomic molecules)
Then make a number 7 on the periodic table
Do not forget the 7th diatomic molecule
Rules:1. The formula is written with the more
electropositive element (the one further to the left on the periodic table) placed first, then the more electronegative element (the one further to the right on the periodic table). Example : CO2
[Important exception: when the compound contains oxygen and a halogen, the halogen is placed first. If both elements are in the same group, the one with the higher period number is named first.]Example: Cl2O.
2. The second element’s name ends in –ide
3. Never use the prefix mono with the 1st word.
4. Do not put two O’s together
Naming covalent bondsPrefixes are used for the number of atoms1 – mono2 – di3 – tri4 – tetra5 – penta6 – hexa7- hepta8- octa9- nona10 - deca
Examples:
CO2 –
CO –P4Cl3 -
Carbon DioxideCarbon monoxideTetraphosphorous trichloride
How will two oxygen atoms bond?
OO
O2
Oxygen is one of the diatomic molecules
OOEach atom has two unpaired electrons
OO
OO
OO
OO
OO
OO
Oxygen atoms are highly electronegative.
So both atoms want to gain two electrons.
OO
Oxygen atoms are highly electronegative.
So both atoms want to gain two electrons.
OO
OO
OO
OO
OO
OOBoth electron pairs are shared.
6 valence electronsplus 2 shared electrons
= full octet
OO
6 valence electronsplus 2 shared electrons
= full octet
OO
two bonding pairs,
OOmaking a double bond
OO=For convenience, the double bond
can be shown as two dashes.
OO
OO=This is the oxygen molecule,
O2
this is so
cool!!
Triple bonds are when three sets of electrons are shared.
Some covalent bonds can have morethan one bond type.
OFCOVALENT
COMPOUNDS
Since electrons do not like each other, because of their negative charges, they orient themselves as far apart as possible, from each other.
This leads to molecules having specific shapes.
•Atoms bond to form an Octet (8 outer electrons/full outer energy level)
•Bonded electrons take up less space then un-bonded/unshared pairs of electrons.
•Number of Bonds = 2
•Number of Shared Pairs of Electrons = 2
•Bond Angle = 180°
EXAMPLE:
BeF2
•Number of Bonds = 2
•Number of Shared Pairs of Electrons = 2
•Number of Unshared Pairs of Electrons = 2
•Bond Angle = < 120°
EXAMPLE:
H2O
•Number of Bonds = 3
•Number of Shared Pairs of Electrons = 3
•Number of Unshared Pairs of Electrons = 0
•Bond Angle = 120°
EXAMPLE:
GaF3
•Number of Bonds = 3
•Number of Shared Pairs of Electrons = 4
•Number of Unshared Pairs of Electrons = 1
•Bond Angle = <109.5°
EXAMPLE:
NH3
•Number of Bonds = 4
•Number of Shared Pairs of Electrons = 4
•Number of Unshared Pairs of Electrons = 0
•Bond Angle = 109.5°
EXAMPLE:
CH4
•Number of Bonds = 5
•Number of Shared Pairs of Electrons = 5
•Number of Unshared Pairs of Electrons = 0
•Bond Angle = <120°
EXAMPLE:
NbF5
•Number of Bonds = 6
•Number of Shared Pairs of Electrons = 6
•Number of Unshared Pairs of Electrons = 1
•Bond Angle = 90°
EXAMPLE:
SF6
Draw the following and state the shape1.CCl4
2.O2
3.SBr2
4.NI3
