Covalent Compounds
January 2015
Covalent Compounds
 Covalent
Bond –
chemical bond that
results from sharing
electrons
 Molecule
– formed
when two or more
atoms are bonded
covalently
Naming Binary Compounds
1.
First element named first
2.
Second elements ending is changed to –ide
3.
Use prefixes to indicate the number of
each atom

Examples:

N2O – dinitrogen monoxide

CCl4 – carbon tetrachloride
Prefixes
1.
Mono –
2.
Di-
3.
Tri-
4.
Tetra-
5.
Penta-
6.
Hexa-
7.
Hepta-
8.
Octa-
9.
Nona-
10.Deca-
Diatomics
 There
are seven elements that always exist
as diatomics
 Always
exist bonded to themselves in nature
 Example:
H
H2
BrONClIF or BrINClHOF
Practice – Name or give the Formula
1.
NF3
1.
Carbon disulfide
2.
P2O5
2.
Selenium
3.
F2
3.
Nitrogen trihydride
4.
OBr2
4.
Sulfur dioxide
5.
BF3
5.
Phosphorous pentabromide
6.
CH4
6.
Xenon hexafluoride
7.
NO
7.
Tetraarsenic decoxide
8.
BN
8.
Trinitrogen nonoxide
Answers
1.
Nitrogen trifluoride
1.
CS2
2.
Diphosphorus pentoxide
2.
Se
3.
Fluorine
3.
NH3 (ammonia)
4.
Oxygen dibromide
4.
SO2
5.
Boron trifluoride
5.
PBr5
6.
Carbon tetrahydride
6.
XeF6
7.
Nitrogen monoxide
7.
As4O10
8.
Boron mononitride
8.
N3O9
Naming Binary Acids
 Contains
Hydrogen and one other element
 The
first word has the prefix hydro- , the
rest of the first word consists of the root of
the second element plus the suffix –ic
 The
second word is always acid
 Example
 HCl
: hydrochloric acid
 H2S
: hydrosulfuric acid
Practice

HBr

Hydrobromic acid

HI

Hydroiodic acid

H3P

Hydrophosphoric acid

Hydrofluoric acid

HF

Hydroselenic acid

H2Se

Hydrochloric acid

HCl
Naming Oxyacid's

Contains both a hydrogen and an oxyanion
(polyatomic)

Keep the root of the oxyanion

Include prefixes per- and hypo- as part of the name

If the oxyanion ends in –ate replace with –ic

If the oxyanion ends in –ite replace with –ous

The second word is acid
 Example
 HNO3
: nitric acid
 HClO
: hypochlorous acid
Practice

H2SO4

Sulfuric acid

HClO4

Perchloric acid

H3PO4

Phosphoric acid

Carbonic acid

H2CO3

Acetic acid

HC2H3O2

nitrous acid

HNO2
What is the formula for
hydroxic acid?
 H2O
 HOH
Formation of Covalent Bonds
Look at Fluorine

Fluorine has 7 valence electrons, it needs 1 more
electron to form an octet

As two fluorine atoms approach one another
attractive forces and repulsive forces act upon
the two atoms

Once that atoms are close enough together they
bond covalently to form a fluorine molecule.
Structures
Electron Dot Structure
Lewis Structure
Practice – Lewis Structures
1.
PH3
2.
H2S
3.
CCl4
Answers
1.
or
2.
or
3.
or
Single Covalent Bonds
 They
are also called sigma bonds (σ)
 Sigma
bonds occur when the shared pair of
electrons is centered between the two
atoms
Multiple Covalent Bonds
 Atoms
can share more than one pair of
electrons with another atom
 Double
or Triple bonds
 Oxygen
and Nitrogen
 Multiple
covalent bonds consist of one sigma
and at least one pi bond (π)
 Pi
bonds form when parallel orbitals overlap
and share electrons
How many Sigma and Pi bonds are there?
C2H4
C2H2
More Lewis Structures
1.
NF3
2.
CO2
3.
SiF4
4.
CH4
5.
OCl2
6.
NCl3