Chapter 6 - Steven Flashcards
What are hydrocarbons?
Compounds that only contain carbon and hydrogen.
If an organic compound contains elements other than carbon and hydrogen, is it a hydrocarbon?
No
What are carbohydrates?
Compounds which contain carbon, hydrogen and oxygen.
What does the -ate part of carbohydrate show?
That it contains oxygen.
What does saturated mean?
The compound only contains single bonds.
What does unsaturated mean?
A compound containing 1 or more multiple bonds.
What is a multiple bond?
2 or more covalent bonds between 2 atoms.
Are alkanes saturated or unsaturated?
Saturated
Are alkenes saturated or unsaturated?
Unsaturated
What is an organic compound?
A compound containing carbon
What is the displayed formulae?
Formula which shows every atom and every bond separately.
What is the structural formulae?
Formula where you do not show the individual atoms (e.g CH3 - CH2 - CH3)
What is the skeletal formulae?
Formula that shows the only bonds between the carbon atoms. Every change in direction means there is a new carbon atom.
What is the molecular formulae?
They only show how many atoms there are in the whole compound.
What is the empirical formulae?
The simplest ratio of atoms.
When the numbers in the molecular formula cannot be simplified, what does it tell you?
The molecular formula and empirical formula are identical.
What is a functional group?
An atom or group of atoms in a molecule that is responsible for its chemical reactions.
What is a homologous group?
A family of compounds with the same functional group, which differ in formula by CH2 each time.
In a homologous group, what does each compound increase by in terms of Carbons and Hydrogens?
CH2
Do alkanes have a functional group?
No
Do alkanes form a homologous series?
Yes
What is the general formula of alkanes?
CH2+2
What is the functional group of alkenes?
The carbon=carbon double bond
What is the general formula of halogenoalkanes?
CnH2n+1X
What is the general formula of alcohols?
CnH2n+1OH
What is the functional group of alcolohols?
The OH bond
When alkanes are burned completely in air, what do they form?
Carbon dioxide and water
What happens to the boiling temperature of alcohols as you go down the homologous series?
It increases
What is ‘Nomenclature’?
The detailed rules needed for naming very complicated compounds.
How many carbon atoms does methyl indicate?
1
How many carbon atoms does ethyl indicate?
2
How many carbon atoms does propyl indicate?
3
How many carbon atoms does butyl indicate?
4
How many carbon atoms does pentyl indicate?
5
What do you do if there is 2 of the same type of prefix?
You put a ‘di’ infront of it.
e.g. dimethyl or diethyl
What do you do if there is 3 of the same type of prefix?
You put a ‘tri’ infront of it.
e.g. trimethyl or triethyl
If the C=C bond is between the 2nd and 3rd carbon atom of butene, what is the molecule calles?
But-2-ene
What do all alcohols end in?
-ol
What is a prefix?
A set of letters written at the beginning of the molecule
What is a suffix?
A set of letters written at the end of a name
What is a locant?
A number used to indicate which carbon atom in the chain an atom or group is attached to.
What is the suffix of alkenes?
-ene
What is an addition reaction?
A reaction where 2 or more molecules join together to form a larger molecule.
What is a polymerisation reaction?
A reaction where lots of simple molecules form a giant molecule
What is an elimination reaction?
When a small group of atoms break away from a larger molecule.
What is a substitution reaction?
A reaction where one species is replaced by another
What is a hydrolysis reaction?
Splitting a molecule into 2 new molecules by adding H+ and OH- derived from water.
What is an oxidation reaction?
A reaction when a species loses electrons
What is a reduction reaction?
A reaction when a species gains electrons
What are mechanisms?
Diagrams that break reactions down into individual stages to show how substances react together
What does the curly arrow in a mechanism show you?
How electron pairs move around.
In a mechanism, what does the curly arrow point to?
Where the new bond is being formed at the end of the reaction.
In a reaction between chloromethane and aqueous potassium hydroxide, what is formed?
Methanol and potassium chloride
In the reaction between chloromethane and aqueous potassium hydroxided, what happens?
- The carbon-chlorined bond breaks, and the electrons move to the chlorine atom
- Electrons move from the hydroxide to the carbon to form a new bond
What are the 3 types of mechanisms?
- Radical substitution
- Electrophilic addition
- Nucleophilic substitution
What are nucleophiles?
Electron pair donors
Are nucleophiles usually positively or negatively charged?
Negatively charged ions
Why are nucleophiles attracted to places that are electron poor?
Because they are electron rich.
What is a polar bond?
A covalent bond between 2 atoms where the electrons forming the bond are unequally distributed.
Do nucleophiles usually react with positive or negative ions?
Positive ions
What do S+ and S- show?
Partial charges
What are nucleophiles attracted to in a polar carbon-halogen bond?
The C S+ atom
What is nucleophillic substitution?
When the nucleophile takes the halogen’s place in the original carbon-halogen bond
What are electrophiles?
Electron pair acceptors.
Are electrophiles usually positively or negatively charged?
Positively charged
Are electrophiles electron poor or electron rich?
Electron poor
What are electrophiles attracted to?
Areas that are electron rich
Where do electrophiles usually react?
The electron-rich area around a C=C bond/
What is electrophillic addition?
When an electrophile is strongly attracted to the C=C bond
What are radicals?
Atoms with an unpaired electron.
Why are radicals very reactive?
Becuase they have unpaired electrons
What do radicals react with?
Anything
What makes 2 molecules isomers of each other?
If they have the same molecular formula but the atoms are arranged differently
What are the 2 types of isomers?
- Structural isomers
- Steroisms
What are the 3 types of structural isomers?
- Chain isomers
- Positional isomers
- Functional group isomers
What are chain isomers?
The carbons skeleton can be arranged in many ways, can be straight chain or branched.
Give an example of chain isomers:
Butane and methylpropane
What are positional isomers?
Where the functional group is attached to a different carbon atom
What type of structural isomers are Butan-1-ol and Butan-2-ol?
Positional isomers
What are functional group isomers?
Where the same atoms can be rearranged into different functional groups
What are alkanes?
Saturated hyrdocarbons
What is the general formula of alkanes?
CnH2n+2
What is bond fission?
Breaking a covalent bond
What is heterolytic fission?
When the bond breaks unevenly with one of the bonded atoms receiving both electrons.
X-Y –> X+ + Y-
What is formed as a result of heterolytic fission?
A positively charged cation and a negatively charged anion.
What is homolytic fission?
When the bond breaks evenly and each bonding atom recieves one electron from the bonded pair.
What is formed as a result of homolytic fission?
Uncharged radicals
What are photochemical reactions?
Reactions started by ultraviolet light
What are the 3 stages of the reaction mechanism for radical substitutions?
Initiation, Propagation and termination
How are radicals produced in initiation reactions?
- Sunlight provides enough energy to break the Cl-Cl bond
- Each atom gets one electron.
- The atom becomes a radical due to its unpaired electron
What is photodissocation?
When energy from the sun breaks a bond
What happens to the chlorine radical in a propagation reaction?
- Cl attacks a methane molecule
- The new methy radical (CH3( can attack another Cl2 molecule
- The new Cl radical can attack another CH4 molecule, and so on until all the CH4 and Cl2 molecules are wiped out
What happens to radicals in termination reactions?
They are destroyed
If two free radicals join together, what do they form?
A stable molecule
What happens in the termination reaction?
The different possible radicals join together
What is the problem with termination reactions?
You end up with a mixture of products.
Why do you get a mixture of products in a termination reaction?
Because there might be too much of one thing in the reaction and not enough of the other
What is petroleum?
Crude oil
What is petroleum a mixture of?
Small alkanes to massive alkanes
How do you split up crude oil?
Through fractional distillation
What is the 1st stage of fractional distillation?
Vaporizing the crude oil at 350C
What happens to the vaporized crude oil?
It rises through the trays, the larger hydrocarbons don’t vaporize as their boiling points are too high
What happens to the crude oil as it goes up the fractionating column?
It gets cooler, meaning fractions are drawn off at different levels in the column
In fractional distillation, what happens to the hydrocarbons with the smallest boiling points?
They’re drawn off as gases at the top of the column
What is hydrocarbon cracking?
Breaking the C-C bond, which results in multiple hydrocarbons being formed.
What are the 2 types of cracking?
- Thermal cracking
- Catalytic cracking
What does thermal cracking produce?
Lots of alkenes
What conditions does thermal cracking take place at?
A high temperature and high pressure
What does catalytic cracking use?
A zeolite catalyst at a slight pressure and high temperature
What does catalytic cracking produce?
Aromatic hydrocarbons and motor fuels
What is knocking?
Where alkanes explode in their own accord when the fuel/air mixture in the engine is compressed
What does reforming do?
It converts straight chain hydrocarbons into cyclic hydrocarbons.
What catalyst does reforming use?
Platinum stuck on aluminum oxide
What is a combustion reaction?
When you burn alkanes in oxygen.
What are the products of a combustion reaction?
Carbon dioxide and Water
What can combustion only occur between?
Gases
As alkenes release so much energy, what makes them useful?
They are excellent fuels
How do we generate most of our electricity?
Through fossil fuels
Name 3 pollutants formed from the incomplete combustion of fuels?
- Carbon monoxide
- Soot
- Oxides of sulfur and nitrogen
What is the oxygen in your blood carried around by?
Haemoglobin
-
What does carbon monoxide do in your blood?
It bonds to the haemoglobin before the oxygen, which means less oxygen is carried around your body.
What can acid rain be caused by?
Fossil fuels that contain sulfur
When sulfur is burned, what is produced?
Sulfur dioxide gas, which when dissolved in moisture turns into sulfuric acid
When are oxides of nitrogen produced?
When the high pressure and temperature in a car engine cause the nitrogen and the oxygen in the air to react
What are the consequences of acid rain?
- Destroys trees
- Corrodes building and structures
What do catalyctic converters do?
They get rid of pollutants using a platinum catalyst to change them to harmless gases
What does 2NO + CO —> ?
N2 +CO2
What is the non-renewable source?
A source which will run out
What is a renewable source?
A source which will not run out
What are biofuels made from?
Living matter
How is biodiesel made?
By refining renewable fats and oils
When biofuels are growing, what do they absorb?
Carbon dioxide
What are classified as ‘carbon neutral’?
Biofuels, as they absorb CO2 and produce CO2 when burnt
What is the general formula of alkenes?
CnH2n
What type of bonds are single bonds?
Sigma bonds
When is a sigma bond formed?
When 2 orbitals overlap in a straight line
As there is a high electron density between the 2 nuclei in a sigma bond, what does this mean?
There is a strong electrostatic attraction between the nuclei and shared pair of electrons
What type of bond has a high bond enthalpy?
Sigma bonds
What is the strongest type of covalent bond?
Sigma bonds.
What is a double bond made up of?
A sigma bond and a pi bond.
When is a pi bond formed?
When 2 lobes of 2 orbitals overlap sideways
As the electron density is spread out in a pi bond, what is the electrostatic attraction like?
It is weaker than sigma bonds, so pi bonds have relaticely low enthalpy
What is stronger, a single or double bond?
A single bond is 2x stronger than a double bond
What does planar mean?
The carbons lay in the same plane
What does trigonal planar mean?
The atoms attatched to each double bond are at the corners of an imaginary equilateral triangle.
Why can’t C=C bonds rotate?
Because of the way pi orbitals overlap to form pi bonds
What causes alkenes to form stereoisomers?
The restricted rotation around the C=C double bond.
What are stereoisomers?
Isomers that have the same structural formula but a different arrangement
When do stereoisomers occur?
When the 2 double bonded carbon atoms each have 2 different atoms or groups attatched to them
