Transcript Covalent Bonding

Collect the Crossword
Puzzle Homework
6.2 Covalent
Bonding and
Molecular
Compounds.
H2 Covalent Bond
+
+
-
Covalent Bond Formation
E=0
H-H Distance
Bond Formation
Covalent Bonding (cont.)
A
point is reached where the
attractive and repulsive forces
are balanced and potential
energy is at a minimum.
 Results in a stable covalent
bond.
Why Does Bonding Occur
A bond will form if the
system can lower its
total energy in the
process.
Characteristics of the
Covalent Bond
 Bond
length is the average
distance between two bonded
atoms, that is, the distance of
minimum potential energy.
 Bond energy is the energy
required to break a chemical
bond and form neutral atoms.
Bonding Parameters (cont.)
 For
H2, the bond length is 74 pm
(1 picometer =10-12 m).
 For H2, the bond energy is 436
kJ/mole.
 As bond length decreases the
bond energy increases.
Octet Rule
Chemical compounds tend to
form so that each atom, by
gaining, losing or sharing
electrons, has an octet of
electrons in its highest
occupied energy level.
H2 Molecule
H
1s1

H
1s1

 Filled outer shell like Helium
Octet Rule -- F2 Molecule
 F=1s22s22p5
    
 F=1s22s22p5
    
Octet Rule -- HCl Molecule

H=1s1


Cl = 1s22s22p63s23p5
        
1s 2s
2px 2py 2pz 3s 3px 3py 3pz
Electron Dot Notation
An electron-configuration
notation in which only the
valence electrons of an atom of
a particular element are shown
indicated by dots placed around
the element’s symbol.
Electron Dot Notation
Lewis Structures
A
build on electron dot
notations and electron
configuration notation
 For molecules.
 Most simply, a hydrogen atom,
H2, is represented as H  H
Lewis Structure – H2
H:H
or
H-H
Lewis Structure
 Atomic
symbols represent
nuclei and inner-shell electrons
 Dot pairs or dashes represent
electron pairs in covalent bonds
 Dots adjacent to only one
atomic symbol represent
unshared electrons.
Lewis Structure -- Cl2
Z
= 17
 [Ne] 3s23p5
 Dot Diagram?
 Cl2
 Note: shared pair of electrons
Lewis Structures (cont.)
Note: each Cl is
surrounded by three
pairs of electrons that
are not involved in
bonding but “belong”
to the Chlorine.
Lone Pair/Unshared Pair
A pair of electrons that is
not involved in
bonding, but instead
belongs exclusively to
one atom.
Structural Formula
Indicates the kind, number,
arrangement, and bonds of the
atoms in a molecule.
Ethane...C2H6