Hydrocarbons Flashcards
Hydrocarbons
• Composed of carbon (C) and hydrogen (H)
• Constituents of fossil fuels, plastics, drugs, plants etc
• Occur diverse range of molecular structures and phases:
- Gases (methane, propane)
- Liquids (benzene)
- Solids (paraffin wax, naphthalene)
- polymers (polyethylene and polystyrene)
How are hydrocarbons divided
Aromatic
Aliphatic
>saturated=alkanes,linear or ring,all Bonds are single
>unsaturated=Alkenes or alkynes(c triple bond c),linear or ring,Have double of triple bonds
Displayed formula
Shows all atoms and all bonds present in the organic compound
Molecular formula
-number of each atom present,no information about bonding
Condensed formula
Similar to structural but no bonds shown
Skeletal/line formula
Most h are omitted and lines are c
Structural formula
-Shows the structural arrangement of atoms within a molecule.
-Not all bonds are shown and all atoms indicated using subscript
Alkanes
Simplest class of hydrocarbons
• Each carbon bonded to 4 other atoms
• When naming them, the suffix “ane” is used
• They have the general formula CNH2N+2 where N is an integer
General formula for alkanes
Cnh2n+2
Properties of homologous series
• The same general formula
• Similar chemical properties
• Show a gradual variation in physical properties, such as boiling point
• The difference in the molecular formula between one member and the next is CH2
Naming simple alkanes with substituents (alkyl group)
Step 1: Find the longest continuous carbon chain (parent chain)
Step 2: Identify the type of substituent attached to the parent chain
Step 3: Number the carbon chain so we have the most substituents (side chain) and lowest number at each substituent
Step 4: Write the full name as: number (position of substituent)- substituent name (for each group in alphabetic order) parent name
General formula for alkenes
• CnH2n for non-cyclic compounds
General formula for alkynes
CnH2n-2 for non-cyclic compounds
Functional groups
• Chemical motifs or patterns of atoms
• Display consistent “function”
• Part of hydrocarbon framework via covalent bonds
• Biomolecules contain many different types/combinations of functional groups • Affect structure, solubility and reactivity
7 functional groups
-alcohols
-amino acids(cook or nh2)
-ketone/aldehydes
-dna (phosphate group)
-DNA methylation(ch3)
-protein structure(sh)
Structure of an amino acid
Carboxyl and amine group
Side chain (rgroup)
Sulfhydryl group
-found in cysteine(amino acid)
-2 cysteine residues in close proximity to each other can form a disulfide bridge also called cystine.
-stabilise protein structure
Phosphate group
-sugar phosphate of dna
-charged
-acidic as it releases h+ irons into solution
Methyl Group
• From methane
• Hydrophobic and non polar
DNA methylation
• Change activity of DNA segment without changing sequence
Methylation and how it affects gene expression
Find out
Isomers
• Equal number of atoms of the same element
• Same molecular formula but different arrangement of atoms
• Different structures and properties
Structural Isomerism:
Chain
Positional
Functional group
Stereo-Isomerism:
Geometrical (cis-trans)
Conformational eg cyclohexane
Optical/enantiomers
