6.1 [Introduction to organic chemistry] Flashcards
What are hydrocarbons?
Hydrocarbons are compounds that contain only carbon and hydrogen atoms
What is the difference between a saturated molecule and an unsaturated molecule?
Saturated refers to a compound containing only single bonds.
Unsaturated refers to a compound containing one or more multiple bonds,
If there is no more room for hydrogen atoms then the hydrocarbon is saturated
If there is room for hydrogen atoms then the hydrocarbon is unsaturated.
What are multiple bonds?
Multiple bonds include double and triple bonds (covalent) between 2 atoms.
How are organic compounds distinguished?
Formulae
names
What is displayed formulae?
Displayed formulae shows every atom and every bond separately. In many cases best type of formulae to use
What is structural formulae?
Structural formulae is like a simplified displayed formula the atoms are grouped together and joined to a particular carbon atoms together.
What is Skeletal formulae?
Zig zag line that shows only the bonds between the carbon atoms, every change in direction and every ending means there is a carbon atom, every atom other than carbon an hydrogen needs to be represented.
What is molecular formulae?
Molecular formula shows the number of each type of atoms in a molecular actual number of atoms in the molecule.
What is empirical formulae?
Empirical formulae shows the number of each type of atom in the simplest whole number ratio.
How many carbon chains does each start have?
Meth - 1 methyl
Eth - 2 ethyl
Prop - 3 propyl
But - 4 butyl
Pent - 5 pentyl
Hex - 6 hexyl
What is a functional group?
A functional group in a molecule is an atom or group of atoms that give the compound some distinctive and predictable properties. Responsible for its chemical properties.
COOH is a functional group
What is Homologous series?
Set of compounds with the same functional group, similar chemical properties and physical properties that show a graduation.
What are the alkanes?
Organic compounds mainly used as fuels are the alkanes, not considered to contain a functional group, otherwise form a homologous series, structural formula below.
CH4 - Methane
C2H6 - Ethane
C3H8 - Propane
C4H10 - Butane
What is general formula?
For the compounds in a homologous series can use the general formula to represent all of them this is done by using the letter n for the number of carbon atoms, excluding any in the functional group.
Alkanes : CnH2n+2
Alkenes : CnH2n
Halogenoalkanes : Cnh2n+1X
Alcohols : CnH2n+1 OH
What are the simplest rules of nomenclature?
Number of carbon atoms : This is shown by a code (3 or 4 letters) meth - 1 carbon atom
Prefixes and Suffixes : The presence of atoms other than carbon and hydrogen is shown by adding other letters before or after the code for the number of carbon atoms, bromo an atom of bromine
Multiplying prefixes - The presence of 2 or more identical groups is shown by the use of the prefixes di = 2 tri = 3
Locants - Where the atoms and groups can have different positions in a molecule, number and hyphens are used to show the position the number represents the carbon atom in the longest chain that the atoms and groups are attached to for example 2- = the atom or group is attached to the second carbon atom in the chain
What are the prefixes for the halogens?
What are structural isomers?
Hydrocarbons that can be represented by the same molecular formula but different structural formulae.
What are the 2 types of structural isomerism’s?
Chain isomerism which refers to molecules with different carbon chains, Butane and methylpropane are examples of chain isomers because their carbon chains are different
Position isomerism which refers to molecules with the same functional group attached in different positions on the same carbon chain. Propan-1-ol and propan2-ol are single examples of this
What are Geometric isomers?
The first molecule is cis-but-2-ene. Both methyl groups are on the same side of the double bond both shown above the double bond.
The second molecule is trans-but-2-ene. The methyl groups are on opposite sides of the double bond
What are the general rules for naming organic compounds?
What is Stereoisomerism?
Stereoisomerism refers to 2 different ways to arrange a group of atoms. They have the same molecular formula and structural formula but they have a different arrangement.
Why can’t geometric isomers not exist in alkanes?
There needs to be C=C double bonds for cis and trans isomers to occur. Presence of a double bond leads to restricted rotation so groups attached to the C=C carbon atoms cannot move around. Carbon atoms and their attached hydrogen atoms can roatate freely without restriction.
How can you tell if a compound is a stereoisomer?
Each of the carbon atoms either side of the double bond must have 2 different groups attached to it.
If one or more has the same group attached, alkene cannot show cis-trans isomerism
What is E-Z notation?
Because there are many different groups the idea of 2 identical groups being Cis or trans arrangement cannot work because not 2 groups are the same choosing names using the E-Z system.
How is the E-Z notation worked out?
Work out the part of the name that can be used for both isomers, using the normal nomenclature rules.
Use priority rules to decide which of the 2 atoms on the left of the double bond has higher priority use atomic number.
Do the same for the atoms ion the right side of the molecule.
Now decide if the 2 atoms with the higher priorities are on opposite ends of the molecule. If they are then there is a trans with is E isomer if not it is a Z isomer.
What is the definition of Geometric isomers?
Geometric isomers are compounds containing a C=C bond with atoms or groups attached at different positions.
