Bonding
Valence Electrons
• In the highest energy level
• Determine chemical properties.
• Elements bond to get 8 valence e- (octet
rule)
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Anions, Cations, and Electron Configuration
Cations form by losing valance electrons to take on a
noble gas configuration (ns2np6)
Anions, Cations, and Electron Configuration
Cations form by losing valance electrons to take on a noble gas configuration
(ns2np6)
So Li loses the 2s1 electron to form Li+1.
Mg loses both 3s2 electrons to form Mg+2
Al loses three electrons from 3s23p1 to form Al+3
Anions, Cations, and Electron Configuration
Anions form by gaining valance electrons to take on a noble gas configuration
(ns2np6)
So F becomes F1- by gaining a 2p electron to have the new valance
configuration 2s22p6.
S becomes S2- by gaining two 2p electrons to have the new valance
configuration 3s23p6.
N becomes N3- by gaining three 2p electrons to have the new valance
configuration 2s22p6.
Ionic Compounds
• Made of metal cations (+) and
nonmetal anions (-)
+ ClNa
• Have no charge
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• Solid at room temperature
• High melting points
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• Conduct electric current when
dissolved in water
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Writing Ionic Formulas
Aluminum and oxygen
1. Write each ion with the correct
charge (cations first!)
Al3+
O2-
2. Bring the charge # (NOT the + or
-) down as a subscript and switch
which element it goes to
Al2O3
Naming Ionic Compounds
• Name of the cation
– Roman numeral for cations with mutliple
+ charges
• Name the anion
– ide is single anion
– -ate or -ite is polyatomic
CaF2
Calcium fluoride
Li3PO4
Lithium phosphate
PbS2
Lead (IV) sufide
Covalent Bonds
1. Nonmetal atoms are held
together by sharing electrons
2. low melting and boiling point
3. All phases at room temperature
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Diatomic Molecules
H2, N2, O2, F2, Cl2, Br2, I2, At2
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Naming and Writing Formulas
for Covalent Compounds
Indicate # of each atom using prefixes
(mono, di, tri, tetra, penta, hexa,
hepta, octa, nona, deca)
The first element does not use mono if
there’s only one.
NO2
P2O4
nitrogen dioxide
diphosphorus tetroxide
Lewis Structures
Step 1: Set up the following table to determine bond numbers
Atom
VElectrons
# Needed
S
O
O
O
Total
Step 2: Connect atoms based on bond numbers calculated
Step 3: Fill octets with unshared electrons
VSEPR
THEORY
..
Valence
Shell
Electron
bent
tetrahedaral
Pair
linear
Repulsion
..
Trig planar
Trig pyramid