Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
45 Cards in this Set
- Front
- Back
|
What is Organic Chemistry?
|
The study of carbon, excluding carbon oxides (eg. Carbon Dioxide)
|
|
|
What percentage of chemical compounds do organic compounds make up?
|
90%
|
|
|
Carbon compounds are usually bonded with one or more of which elements?
|
- Sulfur
- Hydrogen - Chlorine - Nitrogen - Oxygen |
|
|
Why does carbon form so many compounds?
|
- Each carbon atom can form four covalent bonds with other non-metallic atoms
- Carbon atoms can form covalent bonds with other carbon atoms - Bonds between carbon atoms can be single, double or triple covalent bonds. |
|
|
Hydrocarbons are made up of which two elements?
|
Carbon and Hydrogen
|
|
|
Which fossil fuels can hydrocarbons be obtained from?
|
- Petroleum (crude oil)
- Coal - Natural Gas |
|
|
What is the difference between SATURATED and UNSATURATED hydrocarbons?
|
SATURATED HYDROCARBONS: Have only single covalent bonds between the atoms
UNSATURATED HYDROCARBONS: contain double or triple covalent bonds. |
|
|
What is a Homologous Series?
|
A series of hydrocarbon compounds in which each member differs from the previous one by -CH2-
Members of a homologous series have similar properties. |
|
|
Alkanes
|
SATURATED HYDROCARBONS, meaning they have only single covalent bonds.
Formula: CnH2n+2 |
|
|
What are isomers?
|
They are organic molecules having the same molecular formula but a different structural formula.
|
|
|
Prefix of hydrocarbons...
|
Meth- 1 (only in alkane group)
Eth- 2 Prop- 3 But- 4 The following prefix go by their geometric shape eg. Oct(agon) - 8 |
|
|
Alkenes
|
UNSATURATED HYDROCARBONS. Each contain 1 double covalent bonds between carbons along chain.
Formula: CnH2n |
|
|
Alkynes
|
UNSATURATED HYDROCARBON. Each contains 1 triple covalent bond between carbon atoms along chain.
Formula: CnH2n-2 |
|
|
Alkyl Groups
|
- Often form a branch in hydrocarbons
- Is an alkane molecule with one less hydrogen atom - CH3 is a methyl group - C2H5 is an ethyl group - C3H7 is a propyl group |
|
|
Forces between Hydrocarbon molecules
|
- Hydrocarbon molecules are non-polar. Therefore weak dispersion forces operates between the molecules.
|
|
|
Why does the boiling and melting temperature of alkanes increase as the molecular size increases?
|
This is dues to the strength of the dispersion forces being strong as the molecule becomes larger and larger and therefore a higher temperature is needed to weaken these bonds.
|
|
|
Volatile
|
Meaning more easily evaporated
|
|
|
Viscosity
|
Is a measure of the 'thickness' of the fluid
|
|
|
Cyclic hydrocarbons
|
Carbon atoms that join together to make ring. Eg. Cyclopentane C5H10
Formula: CnH2n |
|
|
Why is Benzene a weird structure?
|
It has a structural of C6H6...
When the carbon atoms form a ring and a hydrogen atoms branches off each of them, each carbon atoms remain with delocalised electron. These six electrons form a ring within the carbon atoms. |
|
|
Functional Groups
|
Is an atom or group of atoms that influence properties of organic molecules. Compounds with the same functional groups have similar chemical properties.
|
|
|
Alkanols (Alcohols)
|
Contain a Hydroxy functional group (-OH)
The -OH replaces one of the hydrogens of the molecule. Thus makes the molecule polar and therefore hydrogen bonding exists between the molecules. |
|
|
When writing the semi-structural formula for alkanols what must be added with the addition of a carbon atom (eg. from methanol to ethanol)
|
CH2 must be added at each stage
|
|
|
Carboxylic Acid
|
These compounds have a carboxy functional group (-COOH). Like alcohols carboxylic acids are polar molecules.
Has a post fix of 'oic acid' eg. ethanoic acid The -COOH replaces a hydrogen atom on the original molecule. |
|
|
When writing the semi-structural formula for carboxylic acid what must be added with the addition of a carbon atom (eg. from methanoic acid to ethanoic acid)
|
CH2 must be added at each stage
|
|
|
Why is the combustion of alkanes so important?
|
Because alkanes will burn in the presence of oxygen (O2) to give off carbon dioxide (CO2), water and heat energy.
|
|
|
What is the difference between COMPLETE and INCOMPLETE combustion?
|
COMPLETE COMBUSTION: This occurs when there is an excess supply of oxygen... Products can be carbon dioxide and water
INCOMPLETE COMBUSTION: When there is a limited supply of oxygen... Products can be carbon monoxide and water. |
|
|
Addition reactions of ethene
|
These reactions generally involve the double bond being converted to a single bond and a small molecule adding on.
Done to test whether there is a double bond present |
|
|
Polymers
|
Polymers are made by joining together small molecules called monomers
|
|
|
What must be present for addition polymerization to occur?
|
A double covalent bond between two carbon atoms
|
|
|
Low density Polyethene (LDPE)
|
- there are many polymer chains that are branched and further apart from each other...
Properties: low density, soft, flexible and translucent, repels water due to waxy surface eg. Glad wrap, carry bags |
|
|
High density Polyethene (HDPE)
|
- There are a few chains that are closer together without branches.
Properties: more rigid, stronger, opaque than LDPE. Slightly flexible, waxy surface that repels water. eg. Milk bottles, shampoo bottles |
|
|
What is a catalyst in chemical reactions?
|
it speeds up the rate of reactions so they occur quicker and are usually chemicals.
|
|
|
Substitution reactions of alkanes
|
One or more of the hydrogen atoms in an alkane is replaced by a different atoms or functional group.
|
|
|
Condensation Polymerisation
|
When the monomers form to create polymers water is released as they have a pair of functional groups that are able to react together
Functional groups present may be: - COOH (carboxy) and hydroxy (OH) - COOH (carboxy) and anime (NH2) - OH (hydroxy) and hydroxy (OH) |
|
|
Thermoplastic Polymers
|
When thermoplastic polymers (such as polyethene/glad wrap) is warmed, it becomes soft and can be molded. As they cool they go hard again.
The long chain as held together by covalent bonds, between the polymer chains are dispersion forces. |
|
|
Properties of thermoplastic polymers
|
-Stretch easily
- Are flexible - Soften on warming - Melt at a low temperature - Can be shaped by warming and then cooling |
|
|
Degree of branching
|
Less branching means that polymer chains can pack together more closely and therefore more strongly held together strengthening the polymer.
As the chains are more closely packed together this makes the light scatter and therefore less transparent, hence HDPE being opaque. |
|
|
Arrangment of side groups...
ATACTIC and ISOTACTIC |
ATACTIC: the branches are on both sides of the polymer chain
ISOTACTIC: the branches are on only one side of the polymer chain |
|
|
Thermosetting Polymers
|
Once these polymers have been produced and molded, they set hard and cannot be re-melted.
THEY HAVE STRONG COVALENT BONDS BETWEEN THE CHAINS CALLED CROSS-LINKS |
|
|
Properties of Thermosetting Polymers
|
- Are hard and rigid. They will shatter rather than bend
- Do not flex - Burn or char on heating - Do not soften or melt GREATER NUMBER OF CROSS LINKS=THE MORE RIGID THE POLYMER! |
|
|
Elastomers
|
Are polymers that when stretched or pulled out of shape, they will regain their original shape when the stretching force is removed. They have far fewer cross links than thermosetting polymer.
|
|
|
Vulcanusation
|
Controlled amounts of sulfur that are added to the un-linked polymer chains of rubber and heated in this process
|
|
|
CoPolymers
|
A polymer made up of two different monomers alternating in the chain.
|
|
|
Why is recycling important?
|
- Most plastics are very stable and are slow to degrade (non-biodegradable)
- Most plastics are produced from crude oil, coal or natural gas. The production of polymers contributes to the depletion of finite resources. |
