CHAPTER 11-15: Organic Chemistry Flashcards

1
Q

What are hydrocarbons?

A

Compound containing carbon and hydrogen atoms

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2
Q

Define what a HOMOLOGOUS SERIES is.

A

a family of compounds with similar chemical properties whose successive members differ by the addition of a -CH2 group.

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3
Q

Define what a FUNCTIONAL GROUP is.

A

a part of the organic molecule that is responsible for the molecule’s chemical properties.

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4
Q

What are the 3 groups that hydrocarbons can be classified as?

A

1) ALIPHATIC - carbons joined in unbranched or branched chains.
2) ALICYLIC - carbons joined in a ring structure.
3) AROMATIC - some/all carbons found in a benzene ring.

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5
Q

What are the 3 homologous series of aliphatics?

A

1) alkanes
2) alkenes
3) alkynes (triple bonds)

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6
Q

What is an alkyl group?

A

The side chain group on a branched hydrocarbon

eg. methyl / propyl/ butyl etc.

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7
Q

What prefix is given to alicylic alkanes?

A

cyclo -

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8
Q

What is the suffix given to:

a) aldehydes
b) ketones
c) carboxylic acids?

A

a) -al
b) -one
c) -ioc acid

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9
Q

Define what a MOLECULAR formula is.

A

a molecular formula shows the number and type of atoms of each element present in a molecule.

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10
Q

Define what an EMPIRICAL formula is.

A

the smallest/simplest whole number ratio of elements in a compound.

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11
Q

Define what a GENERAL formula is.

A

the simplest algebraic formula for any member of a homologous series.

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12
Q

Define what a DISPLAYED formula is.

A

A displayed formula shows the relative positioning of all of the atoms in a molecule and the bonds between them.

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13
Q

What is a STRUCTURAL formula?

A

A formula using the smallest amount of detail to show the arrangement of the atoms in a molecule.
eg. CH3CH2CH2CH3

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14
Q

Define what STRUCTURAL ISOMERS are.

A

compounds with the same molecular formula but different structural formulae.

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15
Q

What 2 ways are structural isomers formed?

A

1) same functional group but in different position or different longest chain.
2) different functional group. eg. ketones and aldehydes have same molecular formula.

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16
Q

What is HOMOLYTIC FISSION?

A

When each atom of a covalent bond gets one of the electrons shared and two radicals are formed.

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17
Q

What is HETEROLYTIC FISSION?

A

When one of the atoms of a covalent bond gets both of the electrons shared forming a positive ion and a negative ion.

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18
Q

What is a reaction mechanism?

A

a process to show how a reaction takes place to form the products.

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19
Q

What do ‘curly arrows’ show?

A

the movement of electron pairs

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20
Q

What happens during an addition reaction?

A

Two reactants join together to form one product.

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21
Q

What happens during a substitution reaction?

A

an atom/group of atoms is replaces by another atom/group of atoms.

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22
Q

What happens during an elimination reaction?

A

The removal of a molecule to form a larger one.

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23
Q

What properties do alkanes have?

A
  • low reactivity
  • most stable organic compounds
  • saturated hydrocarbons
  • a tetrahedral shape around carbon atom - 109.5º
24
Q

Describe the bonding in alkanes?

A

each carbon is joined to 4 other atoms by single covalent bonds.
these covalent bonds are called SIGMA bonds - a result of the overlap of 2 orbitals, one from each bonding atom.

25
Q

Crude oil contains many different alkanes.

By fractional distillation the range of alkanes can be separated, why?

A

Alkanes have different boiling points.

boiling point increases with increasing chain length.

26
Q

Why does the boiling point increase with the chain length?

A
  • increased surface area
  • more surface contact possible between molecules
  • more/stronger london forces
  • require more energy to overcome
27
Q

Why does branching lower the boiling point?

A
  • Fewer surface points of contact between molecules
  • branches get in the way
  • less london forces
28
Q

Why do alkanes reactivity?

A
  • C-C bonds are non-polar
  • C-C and C-H sigma bonds are strong
  • C-H have similiar electronegativity so also non-polar.
29
Q

When alkanes react with plentiful supply of oxygen what is produced?
(combustion reaction)

A

CARBON DIOXIDE AND WATER

and heat is given off.

30
Q

What is the general formula to work out the reaction of a complete combustion reaction?

A

CxHy + ( x + 0.5y) O2 –> xCO2 + 0.5yH2O

31
Q

What can be formed instead of carbon dioxide when alkanes are reacted with LIMITED supply of oxygen?

A

carbon monoxide

carbon (soot)

32
Q

What is the name of the mechanism when alkanes react with halogens?

A

RADICAL SUBSTITUION

33
Q

What are the 3 steps of radical substitution?

A

1) INITIATION - forming 2 radicals through homolytic fission
2) PROPAGATION
3) TERMINATION - two radicals collide forming a molecule with all electrons paired.

34
Q

What is required for homolytic fission to take place for a radical substitution?

A

UV light to provide the energy to initiate the reaction.

35
Q

Why might there be a mixture of compounds formed from a radical substitution reaction?

A

Further substitution of the hydrogen atom until all hydrogens are replaced by the radical

36
Q

Explain the nature of the double bond of alkenes.

A

3 of the 4 bonds electrons are involved in sigma bonds.
this leaves an electron in the p orbital.
a π bond is formed by the sideways overlapping of the p orbitals above and below the sigma bond between the two carbons.

37
Q

What prevents the rotation around the double bond of alkenes?

A

The densities of the π electrons above and below the carbon- carbon bond.

38
Q

What is the shape/bond around the carbon atom in an alkene? why?

A

TRIGONAL PLANAR - 120º

3 regions of electron density which repel each other as far as possible

39
Q

What are stereoisomers?

A

the same structural formula but a different arrangement of the atoms in space.

40
Q

What are the 2 requirements of E/Z isomers?

A
  • a carbon-carbon double bond

- different groups attached to each carbon atom of the double bond.

41
Q

What is the requirement for a cis/trans isomer?

A

a hydrogen atom attached to each carbon atom of the double bond.

42
Q

Why are alkenes more reactive than alkanes?

A

the π bond means the electrons in p-orbital are more exposed and so the π bond is weaker than the sigma bond and is more readily broken.

43
Q

What are the 3 addition reactions that alkenes undergo and what do they form?

A

1) HYDROGENATION - an alkane
2) HALOGENATION - a haloalkane
3) HYDRATION - an alcohol

44
Q

What is added in hydrogenation and under what condition?

A

a hydrogen atom with a nickel catalyst

45
Q

What happens during an addition reaction to alkenes?

A

an addition of a small molecule across the double bond causes the πbond to break and for new bonds to form.

46
Q

Why does the addition of bromine water to a solution with a c=c present cause the colour to disappear?

A

bromine is added across the double bond to cause the colour change.

47
Q

What conditions is hydration occurred in?

A

addition of STEAM in presence of phosphoric acid/sulfuric acid catalyst

48
Q

Why does electrophilic addition occur in alkenes?

A
  • the double bond in an alkane is of high electron density

- attracts an electrophile

49
Q

What is an electrophile?

A

an electron pair acceptor that is attracted to regions of high electron density.

50
Q

What type of fission occurs in electrophilic addition to the electrophile?

A

HETEROLYTIC FISSION

- goes to the more electronegative atom or towards the atom furthest away from double bond when a dipole is induced.

51
Q

What is the major product?

A

the more stable carbocation.

52
Q

Why are tertiary hydrocarbons most stable?

A

because the more alkyl groups, the more the charge is spread out making the ion more stable.

53
Q

What are polymers?

A

extremely large molecules formed from many repeat units (monomers).

54
Q

How are polymers formed?

A

unsaturated alkenes undergo addition polymerisation to produce long saturated chains.

55
Q

What are the environmental positive aspects and problems of polymers?

A

bad: unbiodegradable
good: low reactivity so suitable for story food, chemicals safely

56
Q

How can you improve the sustainability of waster polymers?

A
  • recycle: decrease landfill use & use of fossil fuels to create more (but has to be sorted)
  • use them to produce heat/energy (as fuel)
  • Feedstock recycling - reclaiming the monomers of the waste polymers to use as raw materials for production of new polymers