Basic concepts Flashcards
What are alkenes
What are alkanes
Hydrocarbons which contain a double covalent bond between two carbon atoms in the molecule
Hydrocarbons which contain a single covalent bond between each carbon atom in the molecule
What is the structural pattern among the alkenes
What is the structural pattern among alkanes
Each carbon atoms needs four bonds. However, has two bond already due to a covalent double bond between the carbon atom.
Each carbon atom needs four single covalent bonds
What are the first four alkenes
What are the first four alkanes
Methene, Ethene, propene, butene
Methane, ethane, propane, butane
What are some examples of functional groups
Carboxylic acids
Alkanes
Alcohols
Amines
Alkenes
Ketone
Esters
What group is alcohol a part of?
The hydroxyl group
What is the structure of an alcohol
A hydrogen is covalently bonded to an oxygen which is covalently bonded to the rest of the molecule.
What are some examples of alcohols
Methanol, ethanol ,propanol, butanol
What are some examples of alcohols
Methanol, ethanol ,propanol, butanol
What suffix is given to the functional group carboxylic acid
-oic acid
What are the first four carboxylic acids
Methanoic acid , Ethanoic acid, propanoic acid, butanoic acid
Uses of Esters:
Gives molecules a sweet smell and makes them useful for perfumes and flavourings
Uses of Ketones:
Makes molecules useful as solvents
Uses of Amines
Can be useful as dyes and useful in making medicines
Why is the displayed formula used so frequently?
The displayed formula provides the clearest visual structure of an organic molecule
Why is the structural formula used?
It is often used when writing equations
What does the empirical formula show
The ratio of atoms in the molecule
What are organic chemicals
Covalent molecules based on the element carbon
Give three examples of organic molecules (draw them out)
Methene, alkane, propan-1-ol
Describe one key feature among carbon atoms
They form four covalent bonds
Describe a key feature among oxygen atoms
They form two covalent bond
Describe one key feature among hydrogen atoms
They form one covalent bond
What is the hydrocarbon chain
A hydrocarbon chain is an organic molecule consisting of nothing else but carbon and hydrogen atoms arranged in a chain.
What group is methanol, ethanol , propan-1-ol a part of
The alcohol group
What is a functional group
The part of the molecules which determines how it reacts
What is a homologous series
A homologous series of organic molecules have the same functional group but each successive member has an additional -CH2
What would the functional group be in Chloromethane,1-chloroethane and 1-chloropropane
The functional group would be chlorine atom
What is a hydrocarbon
A molecule which contains only hydrogen and carbon atoms
What is a saturated hydrocarbon
Hydrocarbons with single covalent bonds between the carbon atoms
What is an unsaturated hydrocarbon
Any hydrocarbons with double or triple covalent bonds between the carbon atoms
What are the first three member of the alkane homologous series
Methane, ethane, propane
What are the prefix for the first ten alkane/enes
Meth, eth, prop, but, pent, hex, hept, oct, non, dec
What is the rule when numbering unbranched carbon chains
To name the molecule you have to show the position of the double bond
This is done by choosing the end which produces the lowest possible numbers
What is a branched chain hydrocarbon
A hydrocarbon molecule with a side chain (branch)
How to identify the name of a branched hydrocarbon molecule
Identify the longest chain of carbon atoms
Look at the number of carbon atoms on the side chain
State the position of the side chain on the main carbon chain by numbering the carbon atom (lowest possible number)
If there are two side chain on the carbon chain both side chains will be mentioned . E.g= 3,3- or 3,5-
What is the rule for side chains when listing organic molecules
Side chains are listed alphabetically
What is the molecular formula
The molecular formula of a compound tells us the actual number of atoms of the elements in that compound
How do you write the molecular formula of a compound
The carbon atoms should be written first then the hydrogen atoms. Any other elements are then listed alphabetically
Disadvantages of the molecular formula
It does not give us any information on the structure of the molecule.( How the atoms are bonded together)
Different compounds can have the same molecular formula
What is the empirical formula
The empirical formula is the simplest whole number ratio of the atoms of each element in a compound
What is the empirical formula of Ethane (C2H6)
CH3
Explain the displayed formula
The displayed formula shows us the relative position of each atom plus all the covalent bonds
Disadvantages of the displayed formula
Does not show accurate bond angles
Explain the structural formula
The structural formula shows how atoms are arranged but does not show us the bonds.
The atoms are shown to bond with each carbon atom in turn
How can the structural formula be shortened
If there is a consecutive pattern among the structural formula brackets can be put around the specific carbon chain and a subscript can be placed outside the bracket to show how many times this pattern is repeated.
E.g:
CH3CH2CH2CH2CH3
CH3(CH2)3CH3
How can you add the side chain on structural formula
In structural formula the methyl group is placed in brackets.
The methyl group is included straight after the parent chain it is attached to is mentioned on the structural formula.
Explain the skeletal formula
It is the simplest possible way to represent the structure in an organic molecule
We do not show the carbon and hydrogen atoms. The functional groups are only shown
The covalent bond between carbon atoms bonds to any functional group shown
Explain the general formula
The general formula is the simplest algebraic formula for a member of a homologous series
What is the general formula for alkanes
CnH2n + 2
How can you use the general formula to find the molecular formula of an organic molecule
Input the amount of carbon atoms the organic molecule has and follow the general formula.
The answer will be the amount of hydrogen atoms in the organic molecule
What is the general formula for alkenes
CnH2n
What is the general formula for the chloroalkanes
CnH2n + 1 (Cl)
What is the general formula for alcohol
CnH2n + 1 OH
Why can CnH2n + 2 not be used for a general formula for alcohol
You need to show the functional group in the general formula
What is a structural isomer
Structural isomers are molecules with the same molecular formula but different structural formulae
What do you need to be aware of with alkenes during structural isomerism
Alkenes have structural isomers which are called cycloalkanes.
What is an example of two structural isomers that have different functional groups
Ethanoic acid and methyl methanoate
What are stereoisomers
Stereoisomers are molecules with the chemical formula but the atoms are arranged differently in space
What condition result in alkenes to have cis/trans isomers
The carbon atom in the double bond must be attached to two different groups
At least one group must be the same on both carbon atoms on the double bond
How can you differentiate between a cis / trans isomer
IF the highest priority group is the same on both sides of the double bond than it is a cis isomer whereas if it was on opposite sides it would be a trans isomer
Draw the cis and trans isomers of but-2-ene
Why does but-1-ene not have any cis / trans isomers
Both carbon atoms on either side of the carbon bond must be bonded to two different groups
At least one of those groups must be the same for both carbon atoms
Why cannot the cis / trans ruling system be used for all isomers
Some alkenes may be bonded to more than 2 different groups on a double bond. Thus the cis / trans rule cannot be used. Thus E / Z is used.
Why can cis-trans isomers only exits in two forms
Unlike single covalent bonds, double bonds has very restricted rotation and thus can only form into two isomers
How is the E / Z naming system used for isomers
We start by looking at the group which is the same on the carbon atoms on either side of the double bond.
If the group is on the same side of he molecule we call this a Z isomer (cis)
If the group is on the opposite side of the molecule we call this the E isomer (trans)
Advantages of the E/Z system over the Cis/trans
The cis/trans system is used when there are two identical groups on each carbon on either side of the alkene. However, when there are two different groups on either side of the carbon on the alkene it does not work. (Only used to see if the same substituent is on the same side or not)
As a result the E/Z naming system is used if there are two different groups. (As it order from which substituent attached to each carbon has higher priority and sees whether they are on the same side or opposite)
Explain how to use the CIP priority rules when using the E / Z naming tule
First we look at the atom attached to the carbons either side of the double bond
The element with the greatest atomic number is given the higher priority
We assign E or Z using the higher priority groups
What is an electrophile
An atom or a group of atoms with low electron density which is attracted to an electron rich centre where it accept a pair of electrons to form a covalent bond
What is a nucleophile
An atom or a group of atoms with high electron density which is attracted to an electron deficient centre where it donates a pair of electrons to form a covalent bond
What is heterolytic bond fission
The covalent bond between two atoms breaks and the more electronegative atom takes both electrons to form a negative and positive ion
What is homolytic fission
The covalent bond breaks between two atoms and each atom takes an electron to form two radicals
What does a curly arrow represent
The movement of an electron pair, showing either heterolytic fission or formation of a covalent bond
What is an addition reaction
The addition of an atom or a group of atoms to a molecule.
What is a substitution reaction
The replacement of an atom, ion or group of atoms by a different atom, ion or group of atoms in a molecule
What is an elimination reaction
The removal of a pair of atoms or group of atoms from a molecule
