TOPIC 3/4: Basic Concepts of Organic Chemistry + Alkanes Flashcards

1
Q

Define: aliphatic

A

Carbon atoms joined to each other in unbranched or branched chains

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2
Q

Define: alicyclic

A

Carbon atoms joined to each other in a cyclic structure

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3
Q

Define: aromatic

A

Some/All of the carbon atoms are found in a benzene ring

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4
Q

Define: homologous series

A

a series of organic compounds with the same functional group which undergo similar chemical reactions

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5
Q

Describe the structural difference between aliphatic and aromatic organic molecules

A
  • aliphatic: carbon atoms joined together in straight, branched chains
  • aromatic: contain 1 or more benzene rings
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6
Q

State the three main types of reaction mechanisms

A
  • addition
  • substitution

-elimination

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7
Q

Explain how branching affects boiling point

A

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

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8
Q

Explain how chain length affects boiling point

A

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

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9
Q

Define: structural isomer

A

same molecular formula but different structural formulae

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10
Q

Why can alkanes not reaction with halogens unless in the presence of UV light?

A

high bold enthalpy of the C-C bond

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11
Q

State the difference between complete and incomplete combustion

A

Complete:
- occurs in excess supply of oxygen to form: CO2 & H2O

Incomplete:
- occurs in limited supply of oxygen to form: CO & H2O

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12
Q

Suggest what might be observed to show that carbon is being formed

A

a sooty flame

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13
Q

State why carbon monoxide can cause dizziness, fainting, loss of consciousness and death in humans

A

CO irreversibly bings to haemoglobin instead of oxygen

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14
Q

State two reasons why alkanes are unreactive

A
  • high bond enthalpy of C-C & C-H bonds
  • very low polarity of sigma bonds present
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15
Q

Define: radical

A

A species with an unpaired electron

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16
Q

State the conditions for initiation

A
  • UV radiation
  • High temperatures (400°C)
17
Q

Define: functional group

A

The part of the organic molecule that is largely responsible for the molecule’s chemical properties

18
Q

State the difference between homolytic and heterolytic fission

A

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

19
Q

General formula for cycloalkanes

A

CnH2n

20
Q

How do you calculate molecular formula

A

Molecular mass / Mr

21
Q

Define: electrophile

A

Electron pair acceptor (Br2)

22
Q

Define: nucleophile

A

Electron pair donor (OH-)

23
Q

Define: unsaturated

A

A compound with a carbon to carbon multiple bond

24
Q

define: saturated hydrocarbon

A

contains only carbon and hydrogen atoms joined together by single covalent bonds

25
Q

how do you calculate volume of a gas at room temperature

A

vol at RTP = mol x 24

26
Q

what do curly arrows represent?

A

the movement of a pair of electrons

27
Q

State the three different types of structural isomerism. (3)

A
  • chain isomerism
  • positional isomerism
  • functional group isomerism
28
Q

State the bond angle in an alkane molecule

A

109.5 oC

29
Q

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)

A
  • ethyne has fewer electrons than ethane
  • the intermolecular forces would be weaker, so the b.p. would be lower
30
Q

Explain why carbon monoxide is dangerous if inhaled. (2)

A
  • CO binds to haemoglobin which therefore cannot bind to oxygen
  • carbon dioxide cannot be removed from the body