Basic Concepts Of Organic Chem & Alkanes Flashcards
Define: aliphatic
Carbon atoms joined to each other in unbranched or branched chains
Define: alicyclic
Carbon atoms joined to each other in a cyclic structure
Define: aromatic
Some/All of the carbon atoms are found in a benzene ring
Define: homologous series
- a series of organic compounds with the same functional group which undergo similar chemical reactions
Describe the structural difference between aliphatic and aromatic organic molecules
- aliphatic: carbon atoms joined together in straight, branched chains
- aromatic: contain 1 or more benzene rings
State the three main types of reaction mechanisms
- addition
- substitution
- elimination
Explain how branching affects boiling point
More branching means that there is less surface area contact between adjacent molecules which leads to less London forces and so less energy is required to overcome them which leads to a lower boiling point
Explain how chain length affects boiling point
As chain length increases, surface area contact increased between adjacent molecules which leads to more London forced which require more energy to overcome, therefore increasing the boiling point
Define: structural isomer
- same molecular formula but different structural formulae
Why can alkanes not reaction with halogens unless in the presence of UV light?
- high bold enthalpy of the C-C bond
State the difference between complete and incomplete combustion
Complete:
- occurs in excess supply of oxygen to form: CO2 & H2O
Incomplete:
- occurs in limited supply of oxygen to form: CO & H2O
Suggest what might be observed to show that carbon is being formed
sooty flame
State why carbon monoxide can cause dizziness, fainting, loss of consciousness and death in humans
CO irreversibly bings to haemoglobin instead of oxygen
State two reasons why alkanes are unreactive
- high bond enthalpy of C-C & C-H bonds
- very low polarity of sigma bonds present
Define: radical
A species with an unpaired electron
State the conditions for initiation
- UV radiation
- High temperatures (400°C)
Define: functional group
The part of the organic molecule that is largely responsible for the molecule’s chemical properties
State the difference between homolytic and heterolytic fission
Homolytic:
- when covalent bond breaks, each bonded atom takes one of shared pair electrons from bond
Heterolytic:
- when covalent bond breaks, one bonded atom takes both electrons from bond
General formula for cycloalkanes
CnH2n
How do you calculate molecular formula
Molecular mass / Mr
Define: electrophile
Electron pair acceptor (Br2)
Define: nucleophile
Electron pair donor (OH-)
Define: unsaturated
A compound with a carbon to carbon multiple bond
define: saturated hydrocarbon
- contains only carbon and hydrogen atoms joined together by single covalent bonds
how do you calculate volume at room temperature
vol at RTP = mol x 24
what do curly arrows represent?
the movement of a pair of electrons
State the three different types of structural isomerism. (3)
- chain isomerism
- positional isomerism
- functional group isomerism
State the bond angle in an alkane molecule
109.5 oC
State, with a reason, whether the boiling point of ethyne would be expected to be higher or lower than the boiling point of ethane. (2)
- ethyne has fewer electrons than ethane
- the intermolecular forces would be weaker, so the b.p. would be lower
Explain why carbon monoxide is dangerous if inhaled. (2)
- CO binds to haemoglobin which therefore cannot bind to oxygen
- carbon dioxide cannot be removed from the body
