Transcript Covalent Bonding and Molecular Compounds

 Molecules
– a neutral group of
atoms held together by covalent
bonds
 Molecular compound – a cmpd
whose simplest units are molecules
 Chemical formula – indicates
relative # of atoms of each kind in
a chemical compound by using
atomic symbols & subscripts
 Molecular
formula – shows
types & # of atoms combined
in a single molecule of a
molecular compound
 Diatomic molecule – a
molecule with only 2 atoms.
 Bond
will form when potential
energy will be at lowest.
 Nature favors situations when
E can be reduced
 Bond
length – the average
distance b/t 2 bonded atoms at
their lowest potential energy
 Bond energy – the E required to
break a chemical bond and
form neutral isolated atoms
 Atoms
want 8 e- in their
valence shell
 There are exceptions like H, He,
and B
 EDN
– an e-config notation in
which only the valence e-are
shown as dots around an
elements symbol
 What is the dot notation for F,
Na, Al, Kr
 L-S
– atomic symbol is nuclei and
inner shell e-’s and dot pairs and
dashes b/t atoms represent e-pairs
in covalent bonds or unshared
pairs
 Structural formula – indicates kind,
#, & arrangement of bonds but not
the unshared pairs of e-’s
H and halogens often bind to 1
other atom and are usually on
the outside or end of a molec.
2. Atom with lowest e-neg is often
central. They have less than 7 eand can form more than 1
bond.
1.
3. When placing valence e-, put
1 e- on each side b4 pairing
e-
 Single
Bond – covalent bond
where 1 pair of e-’s are shared
b/t 2 atoms
 Draw the Lewis structure for …
H2
HF
NaCl
CH4
CH3I
Draw the LS for each element
2. Put least electronegative
element in center
3. Arrange other elements
around central atom to satisfy
octet (H only needs 2)
4. Change dots to lines to show
bonds b/t atoms
1.
5. For unpaired electrons, try to
form multiple bonds.
6. If octets are still not satisfied,
try to move electrons around
molecule.
 Double
bond– 2 pairs of e-’s(4e-)
 Triple Bond – 3 pairs of e-’s (6e-)
 What is the Lewis structure for …
O2
N2
CO2
CH2O
C2HCl
 R.S.
bonding in molecule or
ions that can’t be represented
by a single Lewis Structure
 O3
 Delocalized – e- shared b/t
more than 2 atoms
Complete
the Lewis
Structures for the following…
NH4+
OHCN-
NO2_