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Basic concepts Flashcards

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1
Q

What are alkenes

What are alkanes

A

Alkenes are unsaturated hydrocarbons containing a C=C bond comprising a π-bond which is a sideways overlap of adjacent p-orbitals above and below the bonding C atoms) and a σ-bond which is a direct overlap of orbitals directly between bonding atoms. Alkenes have a restricted rotation of the π-bond.

Alkanes are saturated hydrocarbons containing
single C–C and C–H bonds (σ-bonds) which are direct overlap of orbitals between the bonding atoms these have a free rotation of the σ-bond

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2
Q

What is the structural pattern among the alkenes

What is the structural pattern among alkanes

A

Each carbon atoms needs four bonds. However, has two bond already due to a covalent double bond between the carbon atom.

Each carbon atom needs four single covalent bonds

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3
Q

What are the first four alkenes

What are the first four alkanes

A

Methene, Ethene, propene, butene

Methane, ethane, propane, butane

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4
Q

What are some examples of functional groups

A

Carboxylic acids

Alkanes

Alcohols

Amines

Alkenes

Ketone

Esters

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5
Q

What group is alcohol a part of?

A

The hydroxyl group

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6
Q

What is the structure of an alcohol

A

A hydrogen is covalently bonded to an oxygen which is covalently bonded to the rest of the molecule.

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7
Q

What are some examples of alcohols

A

Methanol, ethanol ,propanol, butanol

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8
Q

What are some examples of alcohols

A

Methanol, ethanol ,propanol, butanol

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9
Q

What suffix is given to the functional group carboxylic acid

A

-oic acid

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10
Q

What are the first four carboxylic acids

A

Methanoic acid , Ethanoic acid, propanoic acid, butanoic acid

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11
Q

Uses of Esters:

A

Gives molecules a sweet smell and makes them useful for perfumes and flavourings

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12
Q

Uses of Ketones:

A

Makes molecules useful as solvents

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13
Q

Uses of Amines

A

Can be useful as dyes and useful in making medicines

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14
Q

Why is the displayed formula used so frequently?

A

The displayed formula provides the clearest visual structure of an organic molecule

It shows all the atoms in an organic molecule and the relative positions of all the bonds

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15
Q

Why is the structural formula used?

A

It is often used when writing equations

Shows minimal detail of how atom are arranged and shows which atoms are bonded to which (Without drawing bonds)

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16
Q

What does the empirical formula show

A

The ratio of atoms in the molecule

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17
Q

What are organic chemicals

A

Covalent molecules based on the element carbon

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18
Q

Give three examples of organic molecules (draw them out)

A

Methene, alkane, propan-1-ol

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19
Q

Describe key feature among carbon atoms

A

They form four covalent bonds

Can form different bonds types

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20
Q

Describe a key feature among oxygen atoms

A

Oxygen atoms have six electrons in their outer shell, so they typically form two covalent bonds

Highly electronegative and forms polar bond

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21
Q

Describe a key feature among hydrogen atoms

A

They form one covalent bond

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22
Q

What is the hydrocarbon chain

A

A hydrocarbon chain is an organic molecule consisting of nothing else but carbon and hydrogen atoms arranged in a chain.

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23
Q

What group is methanol, ethanol , propan-1-ol a part of

A

The hydroxyl group

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24
Q

What is a functional group

A

A group of atoms responsible for the characteristic reactions of a compound

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25
What is a homologous series
A homologous series of organic molecules have the same functional group and general formula but each successive member has an additional -CH2
26
What would the functional group be in Chloromethane,1-chloroethane and 1-chloropropane
The functional group would be chlorine atom
27
What is a hydrocarbon
A molecule which contains only hydrogen and carbon atoms
28
What is a saturated hydrocarbon
Hydrocarbons with single covalent bonds between the carbon atoms
29
What is an unsaturated hydrocarbon
Any hydrocarbons with double or triple covalent bonds between the carbon atoms
30
What are the first three member of the alkane homologous series
Methane, ethane, propane
31
What are the prefix for the first ten alkane/enes
Meth, eth, prop, but, pent, hex, hept, oct, non, dec
32
What is the rule when numbering unbranched carbon chains
For unbranched molecules, number the carbon chain from the end closest to the highest priority functional group.
33
What is a branched chain hydrocarbon
A hydrocarbon molecule with a side chain (branch)
34
How to identify the name of a branched hydrocarbon molecule
Find the longest continuous carbon chain This gives the parent name Number the chain by stardust from the end that gives the lowest number to the first branch. Identify and name side chains (alkyl groups) then assign numbers to side chains by Showing where each side chain is attached. List side chains in alphabetical order and use prefixes if needed (di-, tri-, etc.) Use hyphens and commas correctly (g. 2,3-dimethylbutane)
35
What is the rule for side chains when listing organic molecules
Side chains are listed alphabetically If there are multiple side chains then you use prefixes (di/tri/tetra)
36
What is the molecular formula
The molecular formula of a compound tells us the actual number of atoms of the elements in that compound
37
How do you write the molecular formula of a compound
The carbon atoms should be written first then the hydrogen atoms. Any other elements are then listed alphabetically
38
Disadvantages of the molecular formula
It does not give us any information on the structure of the molecule.( How the atoms are bonded together) Different compounds can have the same molecular formula
39
What is the empirical formula
The empirical formula is the simplest whole number ratio of the atoms of each element in a compound
40
What is the empirical formula of Ethane (C2H6)
CH3
41
Explain the displayed formula
The displayed formula shows us the relative position of each atom plus all the covalent bonds
42
Disadvantages of the displayed formula
Does not show accurate bond angles
43
Explain the structural formula
The structural formula shows how atoms are arranged in a molecule.It displays the atoms in the order they are bonded
44
How can the structural formula be shortened
If there is a consecutive pattern among the structural formula brackets can be put around the specific carbon chain and a subscript can be placed outside the bracket to show how many times this pattern is repeated. E.g: CH3CH2CH2CH2CH3 CH3(CH2)3CH3
45
How can you add the side chain on structural formula
In structural formula the methyl group is placed in brackets. The methyl group is included straight after the parent chain it is attached to is mentioned on the structural formula.
46
Explain the skeletal formula
The skeletal formula is the simplest way to represent an organic molecule. It shows the carbon skeleton and functional groups only. Line represents covalent bonds
47
Explain the general formula
The simplest algebraic formula for a member of a homologous series
48
What is the general formula for alkanes
CnH2n + 2
49
How can you use the general formula to find the molecular formula of an organic molecule
Input the amount of carbon atoms the organic molecule has and follow the general formula. The answer will be the amount of hydrogen atoms in the organic molecule
50
What is the general formula for alkenes
CnH2n
51
What is the general formula for the chloroalkanes
CnH2n + 1 (Cl)
52
What is the general formula for alcohol
CnH2n + 1 OH
53
Why can CnH2n + 2 not be used for a general formula for alcohol
You need to show the functional group in the general formula
54
What is a structural isomer
Structural isomers are molecules with the same chemical formula but different structural formulae
55
What do you need to be aware of with alkenes during structural isomerism
Alkenes have structural isomers which are called cycloalkanes. The double bond can appear in different location Alkenes may have different branches
56
What is an example of two structural isomers that have different functional groups
Ethanoic acid and methyl methanoate
57
What are stereoisomers
Stereoisomers are molecules with the chemical formula but the atoms are arranged differently in space
58
What condition result in alkenes to have cis/trans isomers
Each carbon in the double bond has two different groups, but one group is the same on both sides
59
How can you differentiate between a cis / trans isomer
If the same group is on the same side of the double bond it is Cis If the same group is on opposite sides of the double bond it is Trans
60
Draw the cis and trans isomers of but-2-ene
61
Why does but-1-ene not have any cis / trans isomers
Each carbon in the double bond must be bonded to two different groups. However, in but-1-ene one carbon atom is bonded to two hydrogen atoms
62
Why cannot the cis / trans ruling system be used for all isomers
Cis/ trans can only be used when there is an identical group on either side of the carbon double bond which all isomers do have
63
Why can cis-trans isomers only exits in two forms
Unlike single covalent bonds, double bonds has very restricted rotation and thus can only form into two isomers
64
How is the E / Z naming system used for isomers
We start by looking at the group which is the same on the carbon atoms on either side of the double bond. If the group is on the same side of he molecule we call this a Z isomer (cis) If the group is on the opposite side of the molecule we call this the E isomer (trans)
65
Advantages of the E/Z system over the Cis/trans
The Cis/Trans system is used when each carbon on the C=C bond has two identical substituents (e.g., both carbons have a hydrogen and another identical group). Cis: identical groups on the same side. Trans: identical groups on opposite sides. However , it doesn’t work when each carbon has two different substituents. Therefore, we use the E/Z system which is used when each carbon has two different substituents. we assign priority to groups on each carbon using CIP rules to determine either E/Z
66
Explain how to use the CIP priority rules when using the E / Z naming tule
First we look at the atom attached to the carbons either side of the double bond The element with the greatest atomic number is given the higher priority We assign E or Z using the higher priority groups
67
What is an electrophile
An atom or a group of atoms with low electron density which is attracted to an electron rich centre where it accept a pair of electrons to form a covalent bond
68
What is a nucleophile
An atom or a group of atoms with high electron density which is attracted to an electron deficient centre where it donates a pair of electrons to form a covalent bond
69
What is heterolytic bond fission
The covalent bond between two atoms breaks and the more electronegative atom takes both electrons to form a negative and positive ion
70
What is homolytic fission
The covalent bond breaks between two atoms and each atom takes an electron to form two radicals
71
What does a curly arrow represent
The movement of an electron pair, showing either heterolytic fission or formation of a covalent bond
72
What is an addition reaction
The addition of an atom or a group of atoms to a molecule.
73
What is a substitution reaction
The replacement of an atom, ion or group of atoms by a different atom, ion or group of atoms in a molecule
74
What is an elimination reaction
The removal of a pair of atoms or group of atoms from a molecule
75
What is the general formula for alkyl groups
CnH2n+1
76
Define an aliphatic compound
A compound containing carbon and hydrogen joined together in straight chains, branched chains or non-aromatic rings
77
Define alicyclic
An aliphatic compound arranged in non-aromatic rings with or without side chains
78
79
Define an aromatic compound
A compound containing a benzene ring
80
Draw the 3D structure of methane
81
Draw the 3D structure of ethane
82
Draw the 3D structure of methane
83
Why type of bond accounts for each type of hybridisation (sp,sp2,sp3)
Sp (triple bond) Sp2 (double bond) Sp3 (single bond)

Chemistry A-level (36 decks)

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