Module 4: Chapter 11&12 Organic Chemistry & Alkanes Flashcards Preview

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Flashcards in Module 4: Chapter 11&12 Organic Chemistry & Alkanes Deck (32)
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Define general formula

The simplest algebraic formula of a member of a homologous series e.g. CnH2n+2


Define structural formula

The minimal detail that shows the arrangement of atoms in a molecules e.g. CH3CH2CH2CH3


Define displayed formula

Shows the relative positioning of atoms and the bonds between them


Define skeletal formula

Simplified organic formula, shown by removing hydrogen atoms from alkyl chains, leaving just a carbon skeleton and associated functional groups


Define homologous series

A series of organic compounds having the same functional group but with each successive member differing by CH2


Define functional group

A group of atoms responsible for the characteristic reactions of a compound
- alkanes is the only family that doesn't have a functional group


Define aliphatic

A compound containing carbon and hydrogen joined together in straight chains, branched chains or non-aromatic rings


Define alicyclic

An aliphatic compound arranged in non-aromatic rings with or without side chains


Define aromatic

A compound containing a benzene ring


Define saturated

A molecule with single carbon to carbon bonds only


Define unsaturated

A molecule with multiple carbon-carbon bonds including double and triple carbon-carbon bonds and aromatic rings


Define structural isomers

compounds with the same molecular formula but with a different structural formulae


Define homolytic fissions

When a bond breaks and each bonding atom receives one electron from the bonded pair to form 2 radicals


Define heterolytic fission

When a bond breaks and one bonding atom receives both electrons from the bonded pair to form ions


Define radical

A species with an unpaired electron


What are the rules for naming alkanes?

1. find the longest continuous carbon chain
2. identify any substituent group
3. number carbon atoms in longest chain to indicated position of any substituent groups (start numbering from the end that produces lowest set of numbers)
4. if same alkyl group appears more once indicated in name with di-, tri- and tetra- and use commas to separate numbers
5. names of different substituents are arranged alphabetically regardless of numbers


Why is carbon special?

- all carbon compounds are covalent
- each carbon atom forms 4 covalent bonds
- carbon forms strong covalent bonds with itself to form rings and chains


What are hydrocarbons?

only contain carbon and hydrogen and have the general formula CxHy


What is the molecular formula?

Gives the number of different types of atom in the molecule


What is the empirical formula?

Gives the ratio of the different types of atom in the molecule


What are the 3 types of structural isomers?

Chain, position and functional group


Describe position isomerism

in compounds containing a functional group, the functional group can be at different positions along the carbon chain


Describe functional group isomerism

molecules containing different functional groups have the same molecular formula


What are alkanes?

- hydrocarbons; they contain carbon and hydrogen only
- they are saturated, only single carbon-carbon bonds
- general formula of CnH2n+2


What are the first 10 alkanes?

methane (CH4)
ethane (C2H6)
propane (C3H8)
butane (C4H10)
pentane (C5H12)
hexane (C6H14)
heptane (C7H16)
octane (C8H18)
nonane (C9H20)
decane (C10H22)


What are the bonds and shape of alkanes?

- Alkanes contain single C-C bonds
- 2 s orbitals overlap to form a bond between the 2 carbon atoms that share a pair electrons, this is a sigma (σ) bonds
- alkanes have a tetrahedral structure with a bond angle of 109.5°


What are the boiling points of alkanes?

The boiling point is determined by the intermolecular force present and the size of the molecule (chain length)
- in crude oil there are lots of variations of boiling points so oil refineries separate crude oil into fractions by fractional distillation
- the greater the chain length, the greater the London forces, the higher the boiling point
- longer chains have a larger surface area, more contact between molecules, London forces are greater, more energy required to overcome forces
- same applies to the shape of the chain, the more branching, the less surface area of contact and the weaker the London forces


What is the alkane reactivity?

- strong sigma bonds throughout
- non polar bonds throughout
- generally not very reactive


Describe combustion of alkanes?

- alkanes combust very well
- in plentiful supply of oxygen complete combustion results in the production of H2O and CO2


Describe the incomplete combustion of alkanes?

Most fuels don't burn completely in oxygen. Either CO and H2O or C and H2O are formed
- CO is odourless, colourless, tasteless and highly toxic
(- CH4 is a greenhouse gas 22 more times potent than CO2)