METALLIC BONDING,
COVALENT BONDING &
NAMING
How to determine type of bond




The difference in electronegativity of the bonding
atoms can determine the type of bond that forms
0.0 < ∆EN < 0.5 non polar covalent
0.5 ≤ ∆EN < 1.9 polar covalent
∆EN ≥ 1.9 ionic
Metallic Bonds



Bonds between two metals (not as strong as ionic &
covalent)
Metals lack valence electrons to provide complete
octet when bonding
Can explain bonds between metals using electron
sea model
Electron Sea Model

the atoms in a metallic
solid contribute their
valence electrons to form
a “sea” of electrons that
surrounds metallic
cations
+
+

The electrons are delocalized
 Electrons
aren’t held to any one atom and move about
the positively charged nucleus

The metallic cations are tightly packed to increase
the attraction between the electrons and the cations
Properties of Metallic Bonds

Have extremely high boiling points
 Can’t
easily pull metal atoms away from the cations
and electrons


Malleable & ductile due to the mobility of the
particles (bond is not due to any particular electron
and cation)
Excellent conductors of electricity
 Due

to the movement of electrons
Shiny (high luster)
Alloys


Mixture of two or more elements one of which is a
metal
Why create an alloy?
Covalent Molecules



A compound whose atoms are held together by
covalent bonds is a covalent compound or
molecule
A molecule is a neutral group of two or more
atoms held together by covalent bonds.
A compound is a neutral group of two or more
different elements combined
Properties of Molecular Compounds





Usually a liquid or gas at 25°C
Tend to have lower melting points
Not as hard as ionic compounds
Not highly soluble in water
Do not act as electrolytes
 Electrolyte
solution
– substance that conducts electricity in
Diatomic Molecules


Certain elements are not found alone in nature and
will bond with self
Form Diatomic Molecule (2 of same atom bonded
together) – has form X2
H2 O2 N2 Cl2 Br2 I2 F2
Covalent Multiple Bonds



Will form single, double, triple, and quadruple
bonds
Bond length decreases with increasing number of
bonds
1>2>3>4
Bond strength increases with the number of bonds
4>3>2>1
Naming Covalent Molecules (case 1)


1st non metal keeps its name
2nd non metal gets an –ide ending
 oxide
 Nitrogen  nitride
 Phosphorus ?
 oxygen

Add greek prefixes to show how many atoms are
present (usually only use mono with oxygen)
Naming Covalent Molecules

1.
2.
3.
4.
5.
Must have greek
prefixes
Mono
Di
Tri
Tetra
Penta
Hexa
7.
Hepta
8.
Octa
9.
Nona
10. deca
½ Hemi
6.
Practice