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Chemistry - Week 4 (Organic Compounds (Alkanes (Contain onyl C and H atoms…
Chemistry - Week 4
Organic Compounds
Alkanes
Alkenes
Alkynes
Compounds of carbons
Carbon can form covalent bonds with itself and many other elements, leading to many other molecules
Central of life (e.g. DNA, proteins)
Central to our society - food, fuels, medicines, polymers, dyes, fibres, wood, paper, modern materials and coatings
Representing structures
Molecular formulae
Butane = C4H10
Structural Formulae
CH3CH2CH2CH3
Isomers
Compounds which have the same molecular formula, but atoms arranged in different ways
Alkanes
Contain onyl C and H atoms
Saturated - max Hydrogen for no. of carbons
no of C = n, no. of H = 2n+2
sp^3 hybridised carbon
1 sigma bond
Alkenes
contain one of more C=C bonds
C=n, H=2n
unsaturated
1 sigma bond, 1 pi bond
Alkynes
contains triple bonds
unsaturated
1 sigma bond, 2 pi bonds
Arenes OR Aromatic
Contains one or more benzene-like rings
unsaturated
Benzene reacts differently to alkenes and alkynes = alternating double bonds
benzene has 3 pi bonds
Molecular Orbital Theory
Solving the wave function = molecular orbitals
Electrons occupy the molecular orbitals
Electrons can go nito molecular orbitals, which arise from the overlap of atomic orbitals. Determines sigma and pi orbitals
Rules
Max. 2 electrons per orbital
(wave function)^2 = probability of electron
Hund's Rule is obeyed
Orbitals of equal energy
Cannot have more electrons in destructive then constructive orbitals
Bonding vs. Anti-bonding orbitals
More electrons in anti-bonding orbitals means it is less stable. For bonds to form, more must be in bonding orbital than anti-bonding orbitals
Bonding molecular orbital
Lower in energy, than the atomic orbitals of which it is composed
Anti-bonding molecular orbital
Higher in energy than the atomic orbital of which it is composed
Bond order
indication of bond strength/length
the higher the bond order the stronger the bond
Indicates what type of bond it is. 2 = double bond, 2.5 = somewhere in between triple and double
Calculated by (number of bonding electrons - number of antibonding) / 2
Paramagnetic vs. Diamagnetic
Diamagnetic = paired electrons
Paramagnetic = unpaired electrons
Organic molecules and functional groups
Compounds with the same functional groups undergo similar reactions
Alcohols (- OH)
Aldehydes ( =O -H)
Ketones (=O)
Carboxylic acids (=O-OH)
Classifying carbon atoms
One other carbons = Primary
Two other carbon atoms = secondary
Three other carbons = tertiary
Four other carbon atoms = quaternary
Acetone
Organic Ketone
Organic chemistry
The basis of molecular biology and biochemistry
Hydrocarbons molecules
Simple structure = zigzag arrangement
Every Carbon has four bonds
Every Nitrogen has three bonds
Every Oxygen has two bonds
Every Hydrogen or Halogen has one bond
