Organic (Y1) - Introduction to organic chemistry Flashcards
Basic introduction to organic chem.
What’s a hydrocarbon?
A compound consisting of hydrogen and carbon ONLY.
Define saturated
contain single carbon-carbon bonds only
Define Unsaturated
Contains a Carbon=Carbon double bond
Define Molecular formula
The formula which shows the actual number of each type of atom
Define Empirical Formula
Shows the whole number ratio of atoms of each element.
Define Structural Formula
shows the minimal detail that shows the arrangement of atoms in a molecule, eg for butane: CH3CH2CH2CH3 or CH3(CH2)2CH3
Define Displayed
Show all the covalent bonds and atoms present in a molecule
Think of examples of a displayed formula
When drawing organic compounds add the hydrogen atoms so that H each carbon has 4 bonds.
What’s the skeletal formula?
shows the simplified organic formula, shown by removing hydrogen atoms from alkyl chains, leaving just a carbon skeleton and associated functional Groups.
What’s the functional group?
is an atom or group of atoms which when present in different molecules causes them to have similar chemical properties.
What are Homolgous series and can you think of any examples.
Homologous series are families of organic compounds with the same functional group and Same general formula.
- They show a gradual change in physical properties e.g. B.P.
- Same chemical properties
- Each member differs by CH2 from the last.
The general rules for naming carbon chains
- Count the longest carbon chain and name appropriately.
- Find any branched chains and count how many carbons they contain.
- Add the appropriate prefix for each branch chain.
What’s homolytic fission?
When EACH atom gets ONE electron from the covalent bond - A one headed arrow shows movement of one electron. The bond has broken in the process called homolytic fission.
What is formed after homolytic fission?
2 free radicals are formed.
What’s the definition of a free radical?
A free radical is a reactive species which possess an unpaired electron. Free radicals do not have a charge but are represented with a bold dot.
What’s heterolytic fission?
When one atom gets both electrons - two headed arrows used to represent this.
Define structural isomers
Same molecular formula different structures.
Define Chain isomers
Compounds with the same molecular formula but different structures of the carbon skeleton.
Define Position isomers
Compounds with the same molecular formula but different structures due to different positions of the same functional group on the same carbon skeleton.
Define functional group isomers
Compounds with the same molecular formula but with atoms arranged to give different functional groups.
Define stereoisomers / describe them
Stereoisomers have the same structural formula but different spatial arrangement of atoms.
Why do E-Z isomers exist?
E-Z isomers exist due to restricted rotation about the C=C double bond. Alkenes can exhibit E-Z stereoisomerism.
When do E-Z stereoisomers arise?
a) There’s a restricted rotation around the C=C double bond.
b) There are two different groups/atoms attached to both ends of the double bond.
What’s the priority group?
Priority group: The atom with the bigger atomic number is classed as the priority atom.
Steps to determining the name of E-Z Stereoisomers.
1) Determine the priority groups on both sides of the C=C double bond.
2) If priority atoms on the same side of the double bond it is labelled X from the german zusammen (The Zame Zide).
3) If the priority atom is on the opposite side of the double bond it is labelled E from the german entgegan (The Epposite side).
What are the Cahn-Ingold-prelog (CIP) priority rules?
- Compare the atomic number of the atoms directly attached to each side of the double bond; the atom of higher atomic number is given priority.
- If the atoms are on the same side, consider the atoms at distance 2 from the double bond. Make a list of each atom bonded to the one directly attached to the double bond. Arrange list in order of decreasing atomic number. Compare the lists atom by atom; at earliest difference, the group containing the atom of higher atomic number is given priority.
Effect of EZ stereoisomers on physical properties. What do you think they can do? Think of the polarity and electronegativity of bonds.
Some molecules may be polar and some may be non-polar. The polar molecules tend to have a higher boiling point and melting point because the bonds are stronger and therefore harder to break.
