đŸ”´đŸ”¸2.4 -organic Compounds Flashcards
What is a functional group
The atom/ groups of atoms that gives the compound its characteristic properties
What is an homologous series
A series of compounds with the same functional group
What is a saturated compound
One that contains no C to C multiple bonds
What is a hydrocarbon
A compound of carbon and hydrogen only
What is an unsaturated compound
One that contains C to C multiple bonds (double bonds)
What are organic chemicals
Chemicals produced by living things often containing hydrogen carbon, some oxygen and other elements (nitrogen, sulfur, phosphorous and the halogens)
What does the order of the elements in a functional group determine
Determine which homologous series the compound belongs to
What are alkanes
E.g ethane
Saturated hydrocarbons
E.g Ethane
What are alkenes
E.g Ethene
Unsaturated hydrocarbons with C-C double bond
E.g Ethene
What are halogenalkanes
Compounds in which one or more hydrogen’s in an alkane have been replaced by a halogen
E.g iodoethane
What are alcohols
Compounds containing -OH as the functional group
E.g Ethanol
What are Carboxylic acids
Compounds containing -COOH as the functional group
E.g pentanoic acid
What is the code for 1,2,3,4,5,6,7,8,9 and 10 carbons
Meth Eth Prop But Pent Hex Hept Oct Non Dec
What are the rules for naming compounds
1) find longest carbon chain e.g 5 carbons = pent
2) label C atoms starting from 1 where there is a side chain closest
3) if more than 1 side chain use di for 2, tri for 3 or tetra for 4
4) name the side chains e.g CH3= methyl C2H5= ethyl
5) saturated carbons shown by (ane), C=C shown by (ene), -OH shown by (ol), -COOH shown by (oic acid), halogen shown by halogeno
What is the molecular formula
Shows the atoms, how many of each type there are, in a molecules of a compound e.g C5H12
What is displayed formula
A formulae showing all of the bonds and atoms in the molecule E.g | | | | C-C-C-C - | | | |
What is shortened formula
Shows the groups in sufficient detail that the structure is unambiguous
E.g CH3C(CH3)2CH2Cl
What is skeletal formula
Shows the carbon/hydrogen backbone of the molecule as a series of bonds with any functional groups attached
E.g /\/\/\ =heptane
Name the characteristics for a homologous series
1) same general formula e.g (CnH2n+2 for alkanes)
2) differ from neighbour in the series by CH2
3) same functional groups and :: similar chemical properties
4) physical properties that vary as the Mr of the compound varies
Give 5 examples of homologous series
Alkanes (saturated hydrocarbons) Alkenes (functional group C=C) Alcohols (functional group -OH) Halogenoalkanes (functional group -F, -Cl, -Br, -I) Carboxylic acids (functional group -COOH)
What 3 things can the functional group vary in particular
- melting temperature
- boiling temperature
- solubility in water
What is the empirical formula
Formula of a compound with the atoms of elements in their simplest ratio
Give the empirical formula of ethane
Ethan molecular formula = C2H6
Ratio C:H = 2:6
Simplest ratio = 1:3
Empirical formula = CH3
What is the equation for the ratio of atoms of each element?
Moles (n) = Mass (g) / Ar
Name 2 types of isomerism
Structural and E/Z
What is structural isomerism
Compounds with the same molecular formula but different structural formula
Name the 3 types of structural isomerism
Chain isomerism
Position isomerism
Functional group isomerism
When does chain isomerism usually occur
When carbon chain is arranged differently, usually one is a straight chain and the others branched
E.g CH3CH2CH3 (butane) and 2-methylpropane
When does positional isomerism occur
When the functional group is in a different position in the molecule e.g 1 -chloropropane (CH2ClCH2CH3) and 2 -chloropropane (CH3CHClCH3)
When does functional isomerism occur?
When the functional group in compounds is different e.g C3H6O could be propanal (aldehyde) or propanone (ketone)
What is E-Z isomerism
Isomerism that occurs in alkenes due to restricted rotation about the double bond
Why is E-Z isomerism possible in alkenes but not alkanes
Single bonds in alkanes allow the atoms/groups at either end to rotate freely
The double bond in alkenes restrict rotation due to the π bond
What is a π bond
A bond formed by the overlap of p orbitals on adjacent atoms, often represented as double bonds (C=C)
What is a sigma bond
Strongest type of covalent chemical bond formed by head on overlapping between 2 atomic orbitals. Represented by (C-C)
What is a (Z) isomer
An isomer where groups of the higher priority (highest Ar) are on the same side of the carbon double bond
E.g (Z)-1,2 -dibromoethene
What is an (E) isomer
An isomer where groups with the higher priority (highest Ar) are attached to the carbons on opposite sides of the double bond
E.g (E)-1,2 -dibromoethene
What happens if the groups attached are different e.g
Br Cl
\ /
C = C
/ \
H HBromine has a higher priority than Hydrogen
Chlorine has a higher priority than Hydrogen
Both groups with highest priority are on the same side of double bond :: z isomerism
This is called (Z)1-bromo 2-chloroethene
What effect does the double bond have on the isomers
still take part in characteristic reactions of alkenes as still have double bond
What effect does the restricted rotation have on the substituent groups attached to double bond
Can cause them to behave differently because In the E form the substituent groups are held too far apart to interact, in Z form they are closer
Why do E isomers normally have higher melting/ boiling points than Z isomers
Shape of E molecules means they can fit together more closely :: have stronger intermolecular forces and :: higher melting/boiling temperatures
Give an example of the melting points in an E isomer and Z isomer
(Z) -Butenedoic acid = 130 degrees Celsius
(E) -Butenedioc acid = 286 degrees celcius
What are Van der Waals forces?
Dipole-dipole or temporary dipole-temporary dipole Interactions between atoms and molecules
What states do small hydrocarbon chains have at room temperature?
Gases
What state do longer hydrocarbons have at room temperature?
Liquids and even larger hydrocarbons are solid at room temperature
What structure do all hydrocarbons have, what does this mean
Hydrocarbons are simple covalent molecules, non polar
This mean only temporary dipole-temporary dipole Van der Waals forces are present between molecules (weak)
Why do the van der Waals forces affect melting/boiling temperatures
Intermolecular temporary dipole-temporary dipole forces act between he surfaces of hydrocarbons meaning the more surface there is in contact the more forces will act and the more energy is needed to overcome these forces
What are intermolecular forces
Forces between molecules
What are intramolecular forces
Forces within the same molecule
Why do ‘sausage shaped’ molecules e.g pentane (straight carbon chain saturated with hydrogen’s) have a greater boiling temperature than more spherical molecules with the same molecular formula e.g 2,2 -Dimethylpropane
When bonds are in a spherical formation often very branched (2,2 -dimethylpropane) the area available for surface area contact is very small meaning the lower its boiling temperature as less van der Waals forces can form
Give the boiling points of pentane and 2,2 dimethyl propane
Pentane = 36 degrees
2,2 -dimethylpropane = 10 degrees
