Organic Chemistry & Carbon Bonding Flashcards
Definition of organic chemistry
chemistry of compounds of carbon
massive range of complexity
e.g. methane and than to penicillin
what are the different physical forms of organic compounds?
gases
liquids
waxes
plastics
crystalline solids
coloured or colourless
odoured or odourless
Carbons abilities
Bind strongly to other elements and form strong bonds to itself
Can catenate (form chains of C atoms)
both allow for large range of possible structures
Carbon
Atomic orbitals: 1s2 2s2 2p2
requires 4 extra e-
define: molecular orbital theory
Two singly occupied s orbitals on each H atom combine to form two molecular orbitals
Two atomic orbitals combine to give two molecular orbitals
atomic orbitals must have the sufficient overlap to form covalent bonds
single bond molecular orbital theory
two half filled s orbitals combine
two end on mixing of 2 atomic p orbitals
give a single (sigma) bond
consisting of 2 sigma molecular orbitals
single binding is more stable and lowest energy orbitals
single sigma covalent bond
double bond molecular orbital theory
same principle but with both s and p orbitals combined
both sigma and pi bond formed and combined
DB: overlap end-on
LOOK AT DIAGRAM
form two sigma molecular orbitals
shares 4e- in double covalent bind
uses the e- in the p orbital
overlap 2 closest ends, bonding molecular orbital
lower energy so more stable
creates a sigma covalent bond
DB: overlap side-on
LOOK AT DIAGRAM
for two pi molecular orbitals
shares 4e- the same as before
pi bonding orbital has a lower energy so more stable, shared pair of e-
creates a pi covalent bind
the double bind is therefore both a sigma and pi bond together
What is orbital dehybridisation?
LOOK AT DIAGRAM
one 2s orbital & 3 2p orbitals mixed to give 4sp3 orbitals
instead of the separate energy levels- the 4sp3 orbitals are inbetween
C now forms 4 covalent bonds to filfil octet rule
A hybrid model mathematically and energetically favoured
form an overall tetrahedral shape around C atom
Carbon Bonding
mutual repulsion push orbitals far apart as possible
as they are in a tetrahedral arrangement
Hybrid orbitals
LOOK AT DIAGRAM
CH4
resulting hybrid orbitals designated sp3
result in tetrahedral methane
C-C single bonds
LOOK AT DIAGRAM
Ethane C2H6
3sp3 orbitals mix with S orbital to form 3 sigma bonds with H
1sp3 orbital from 2nd C forms the C-C bond
formed between overlap of 2 sp3 hybrid orbitals
result in sigma bond
tetrahedral shape around the C
C=C double bonds
LOOK AT DIAGRAM
Different hybridisation
1x2s + 2x2p mix giving 3sp2 hybridised orbitals
leaving one unhybridised 2p orbital
3sp2 form a sigma bond
1 2p orbital forms a pi bond
creating a double bond
formed between overlap of 2 sp2 hybrid orbitals and two unhybridised p orbitals
triganol shape around the C atom
ethene forming bonds
each C forms 3 sigma bonds
binds to 2H and 1C (2nd one)
C=C is formed
