3.3.1- Intro to Organic Chemistry (PAPER 2) Flashcards

1
Q

What does IUPAC stand for?

A

International Union of Pure and Applied Chemistry (IUPAC)

This allows us to name organic compounds

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2
Q

What is the empirical formula?

A

The simplest whole number ratio of atoms of each element in a compound.

Eg- ethene is C2H4 but empirical is CH2

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3
Q

What is the molecular formula?

A

The actual number of atoms of each element in a compound.

Or the number of moles of each element in 1 mole of a compound.

Eg- butane molecular= C4H10, empirical= C2H5

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4
Q

What is the general formula?

A

The simplest algebraic formula of a member of a homologous series.

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5
Q

What is the general formula for alkanes?

A

CnH2n+2

n= number of C atoms

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6
Q

What is the general formula for alkenes and cyclic alkenes?

A

CnH2n

n= number of C atoms

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7
Q

What is the structural formula?

A

Shows the arrangement of atoms and the bonds between them if necessary- does not show all the bonds.
Brackets can show longer chains or branches.

Eg- C4H10= CH3CH2CH2CH3
OR CH3(CH2)2CH3

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8
Q

What is the displayed formula?

A

Shows the arrangement of ALL atoms in a molecule and ALL bonds between them

Eg- draw displayed formula for hexane- C6H14

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9
Q

What is the skeletal formula?

A

A ‘stick-like’ drawing that shows the bonds between carbon atoms only. Each ‘corner’ is a carbon atom!

Functional groups are shown, hydrogen and carbon atoms not shown.

Eg- draw the skeletal formula for C6H14

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10
Q

What are the characteristics of a homologous series?

A

A group of organic compounds ALL containing the same functional group.
Molecules from the same homologous series:
* Have similar chemical properties.
* Show a gradual change in physical properties.
* Can be represented by a general formula as they differ from one another by a -CH2

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11
Q

What is the suffix for alkanes and example of CH3CH2CH2CH3

A

suffix= -ane at the end
eg- butane

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12
Q

What is the prefix for branched alkanes and example of CH3CH(CH3)CH3

A

prefix= alkyl- at the beginning
eg- 2-methylpropane

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13
Q

What is the suffix for alkenes and example of CH3CH=CH2

A

suffix= -ene at the end
eg propene

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14
Q

What is the suffix for alcohols and example of CH3CH2OH

another example C4H10O

A

suffix= -ol at the end
eg- ethanol

another example= butan-1-ol: O attached to C, H attached to O

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15
Q

What is the suffix for aldehydes and example of CH3CH2CHO

A

suffix= -al at the end
eg- propanal
DOUBLE BOND BETWEEN LAST C AND O

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16
Q

What is the suffix for ketones and example of CH3COCH3

A

suffix= -one
eg- propanone
DOUBLE BOND BETWEEN MIDDLE C AND O: in-between alkyl group on left and right side.

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17
Q

What is the suffix for carboxylic acids and example CH3CH2CH2COOH

A

suffix= -oic acid
eg- butanoic acid
DOUBLE BOND BETWEEN LAST C AND O, C SINGLE BOND TO ANOTHER O AND H BONDED TO O

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18
Q

What is the prefix for halogenoalkanes and example CH3CH2Br?

A

prefix= fluoro-, chloro-, bromo-, iodo-
eg- bromoethane

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19
Q

What is the prefix/ suffix for cycloalkanes and example C5H10?

A

cyclo-……-ane
eg- cyclopentane (5C)

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20
Q

What are the IUPAC rules for nomenclature (naming) ?

A

1) Count the number of C atoms in the longest unbranched continuous chain- can go up or down as long as it is still C-C.
If C atoms form a ring, use cyclo- in front of stem.
2)Identify any branches/ functional groups or double bonds.
3) Count from the end that gives the lowest number to the functional group/double bond.
4) If the same groups appear more than once, give them a prefix: 2=di, 3=tri, 4= tetra
5) Groups/ branches are arranged alphabetically: eg ethyl before methyl

21
Q

What is the order of importance for functional groups from highest to lowest?

A
  • -COOH (oic acid) *
    -CHO (aldehyde)
    -C=O (ketone)
    -OH (alcohol)
    -triple bond
    -double bond
    -Cl, -Br, -F, -I (halogenalkanes)
    -CH3, -C2H5, -C3H7, -C4H9 (alkyl groups)
22
Q

What do commas and dashes separate?

A

Commas separate numbers,
dashes separate letters from numbers

23
Q

Order of naming?

A

name stem- alkyl group prefix
1 meth- methyl= CH3
2 eth- ethyl= C2H5
3 prop- propyl= C3H7
4 but- butyl= C4H9
5 pent- pentyl= C5H11

24
Q

What does a chemical mechanism show?

A

The movement of electrons during a chemical reaction.

25
Q

How do we show the movement of a pair of electrons?

A

Through curly arrows- these always start from an area with electrons eg a double bond or lone pair.

Half headed arrow= movement of one electron

They point to where the electrons are being moved to/ the formation of a new bond.

26
Q

What is a free radical? +example

A

A very reactive species which possesses an unpaired electron.

Eg- chlorine atom has unpaired electron and 2 electron pairs, bonds with other Cl atoms to form Cl2

Formed by homolytic fission of covalent bonds (equal splitting of electrons)

27
Q

How do we represent the free electron in free radicals?

A

Using a dot ·

Eg ·CH3 (dot above C as it is free radical)

28
Q

How to write the overall equation for free radical substitution?

A

1) For every H atom replaced by F/Cl/Br/I, one molecule of F2/Cl2/Br2/I2 is used and one molecule of HF/HCl/HBr/HI is released.

2) Number of H that are being replaced= number of halogen molecule needed= number of halide released at the end.

Eg- 6H replaced= 6F needed, 6HF released

29
Q

Write the overall FRS equation for CHF2-CH3—–> CBrF2-CBr3

A

CHF2-CH3 + 4Br2—–> CBrF2-CBr3 + 4HBr

30
Q

What occurs during initiation in free radical substitution?

A

When exposed to UV light, a molecule of halogen Cl2/Br2/F2/I2 breaks apart into 2 halogen atom free radicals- F· / Cl· / Br· / I·

Eg iodine: I2—–> 2I·

31
Q

Draw the initiation of Cl2 using curly arrows

A

Cl:Cl 2 curly arrows from electrons, one to each Cl—- > Cl. Cl.

32
Q

What occurs during propagation in free radical substitution?

A

Step 1) alkane/halogenalkane reacts with F· / Cl· / I· / Br· removing a H atom from the alkane/halogenalkane producing HF/ HCl/ HBr/ HI and a C based free radical.

Step 2) C based radical formed in step 1 reacts with F2/ Br2/ I2/ Cl2 to put an atom of F/Br/Cl/I on the C based free radical. This produces halogen free radical F· / Cl· / Br· / I·

33
Q

Write the 2 equations for the propagation of CH3-CH2-CF3—> CH3-CHBr-CF3

A

1) CH3-CH2-CF3 + Br· —–> CH3-C·H-CF3 + HBr

2) CH3-C·H-CF3 + Br2 —– CH3-CHBr-CF3 + Br·

34
Q

What occurs during termination in free radical substitution?

A

2 free radicals from end of propagation reactions collide together to form a molecule which stops the chain reaction.

35
Q

Write the equation for the termination of CF3-CH2F in CH4—–> CF4

A

·CF3 + ·CH2F —-> CF3-CH2F

36
Q

What is the overall free radical substitution reaction between chlorine and methane?

A

CH4(g) + Cl2 (g)—uv–>CH3Cl(g) + HCl (g)

37
Q

What occurs in initiation of the reaction between chlorine and methane?

A

Cl2—–> 2Cl·

38
Q

What happens in propagation of the reaction between chlorine and methane?

A

1) CH4 + Cl· —–> HCl + ·CH3

2) ·CH3 + Cl2 —-> CH3Cl + Cl·

39
Q

What happens in termination of the reaction between chlorine and methane?

A

·CH3 + Cl· —-> CH3Cl
or
·CH3 + ·CH3 —> C2H6
or
·Cl + ·Cl —-> Cl2

40
Q

How to separate the mixture of products?

A

Fractional distillation

41
Q

What are structural isomers?

A

Compounds that have the same molecular formula but a different structural formula/ arrangement of atoms.

42
Q

What are chain isomers?

A

Isomers that have different carbon chains- shorter/longer.

The molecules with more branching have lower boiling points.

Similar chemical properties, slightly different physical properties- straight chain isomers have higher boiling points as they can pack tighter together, branching decreases effectiveness of intermolecular forces less energy needed to separate molecules.

43
Q

Draw and name all chain isomers of pentane: C5H12

A

methylbutane
dimethylpropane

44
Q

What are position isomers?

A

When the functional group is attached to the carbon chain in a different location (on a different C atom).

Similar chemical properties, slightly different physical properties.

Same functional group.

45
Q

Draw and name all position isomers of 1,1-dichloropropane

A

2,2-dichloropropane
1,2-dichloropropane
1,3-dichloropropane

46
Q

What are functional group isomers?

A

Compounds with the same molecular formula which contain different functional groups.

Different chemical and physical properties.

47
Q

What are the common functional group pairs?

A

Alkenes and cycloalkanes: eg C4H8 can be but-1-ene and cyclobutane

Aldehydes and ketones: eg C3H6O can be propanal and propanone

Carboxylic acids and esters: eg C2H4O2 can be ethanoic acid (COOH group) and an ester with a COOC group.

Alcohols and ethers: eg C3H8 can have O-H at end (alcohol) or C-O-C in the chain (ether)

48
Q

Give equations to show how chlorine atoms catalyse the decomposition of chlorine.

A

.Cl + O3 —-> ClO. + O2

ClO. + O3 —-> .Cl + 2O2