-
the behavior of an atom is most determined by
its electron configuration
-
the behavior of a molecule is most determined by
the molecule's shape
-
how do you determine a molecule's shape?
look at the distribution of electrons in the molecule, using a Lewis dot diagram
-
for all atoms that form covalent bonds, the outermost energy level must
have a total of 8 electrons
-
Which covalently bonded electrons don't have 8 electrons in the outermost level?
- hydrogen
- lithium
- beryllium
- boron
- groups 1, 2, & 13
-
lone pairs
unshared pairs of electrons
-
double bonds
share 2 electron pairs
-
each bond of shared electrons and each pair of unshared electrons in the outermost energy level form a
- charge cloud
- repels other charge clouds
- this is the electrostatic repulsion of 2 or more negative charges
-
what determines the arrangement of orbitals?
electrostatic & Pauli exclusions
-
orbital arrangement determines
molecular shape
-
why do electron pairs spread apart as far as possible in a molecule to
minimize repulsion forces
-
shape 1
- if there are 2 pairs of shared electrons around a central atom, the shared pairs will be on opposite sides of the central atom
- Linear molecule
- the angle between the shared pairs is 180
-
shape 2
- if there are 3 pairs of shared electrons around a central atom, a trigonal planar molecule is formed
- the angle between the pairs is 120
-
shape 3
- if there are 4 pairs of shared electrons around a central atom, a tetrahedral molecule is formed
- angle is 109.5
-
shapes 1, 2, and 3 have
no unshared pairs of electrons
-
the repulsion between unshared pairs of electrons is
stronger than the repulsion between shared pairs
-
shape 4
- if there are 3 shared and 1 unshared pair of electrons around a central atom, a pyramidal molecule is formed
- angle is 107
-
shape 5
- if there are 2 shared and 2 unshared pairs of electrons, an angular or bent molecule is formed.
- angle is 104.5
-
shape 6
- if the molecule is closed, a cyclic molecule is formed
- a ring- closed
-
molecules ehich contain atoms bonded by polar covalent bonds will also be polar, unless
the molecules have symmetry, which makes the molecule non-polar
-
hybrid orbitals
form when s & p orbitals overlap in a covalent bond
-
sigma bond
when 2 hybrid orbitals from 2 different atoms form a bond by overlapping directly on a bond axis
-
pi bond
when 2 hybrid obitals from 2 different atoms bond by overlapping sideways, a pi bond is formed
-
a sigma bond forms a
single bond
-
a sigma bond and a pi bond form a
double bond
-
a sigma bond and 2 pi bonds form a
triple bond
-
-
a double bond is a
sigma & pi
-
a triple bond is a
sigma & 2 pi
-
what makes benzene (C6H6) very stable?
overlapping of pi bonds cause the electrons to be shared all around the ring- these are delocalized pi electrons
-
conjugated system
when multiple pi orbitls overlap
-
catenation
the ability of all carbon atoms to form chains of varying lenghts
-
simple hydrocarbons
- use a stem & -ane
- contain only single bonds
- saturated compounds
-
double bonded hydrocarbons
same stem, add -ene
-
triple bonded hydrocarbons
same stem, add -yne
-
isomers
2 or more compounds which have the same molecular formula but have different structural formulas
-
structural isomers
differ only in the position of the carbon atoms in relation to each other
-
positional isomers
differ only in the relative position of a double or triple bond between carbon atoms
-
functional isomers
- contain atoms besides carbon and hydrogen
- named based on the position of their new atoms
- the new atoms form "functional groups"
-
functional groups
- ex: The alcohol group- OH
- when organic compounds contain an alcohol groupd, they end in -ol
-
geometric isomers
composed of the same atoms bonded in the same order but with different order around a double bond
-
cis
on the same side as the double bond
-
trans
on the opposite side of the double bond
-
-
-
-
-
|
|
