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33 Cards in this Set
- Front
- Back
- 3rd side (hint)
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How many electrons can molecular orbitals hold? |
2 |
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What is the type of hybridisation involved when carbon forms 4 single bonds? |
sp3 made when 3 p orbitals mix with an s orbital. |
Involves the mixing of 4 orbitals |
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How does a sigma bond form? |
By the end-on overlap of two atomic orbitals |
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How does a pi bond form? |
By the sideways overlap of parallel atomic orbitals. |
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What hybrid orbitals are involved with a carbon atom in a double bond? |
sp2 hybrid orbitals involving 2 p orbitals and 1 s orbital |
This leaves a remaining p orbital to form a pi bond |
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What is a conjugated system? |
The section of a molecule which has alternate double bonds. |
Benzene has a small conjugated system. |
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Explain why some molecules are coloured. |
The gap between HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) involves an energy gap that is in the visible region. The electrons in HOMO absorb energy to get promoted to LUMO - molecule appears the complementary colour. |
HOMO and LUMO |
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What is a chromophore? |
The group of atoms in a molecule that is responsible for the absorption of light - the conjugated system. |
Chromo means colour! |
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What are stereoisomers? |
Molecules with the same molecular formula but different spatial arrangement of atoms. |
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What is a cis geometric isomer? |
When a molecule has the same groups on the same side of the double bond or cyclic compound. |
Cis is opposite to trans. |
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Why do some molecules have geometric isomers? |
When there is lack of free rotation around a bond (contain double bond or cyclic) |
No movement |
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What is an optical isomer? Also known as enantiomer or chiral molecules. |
Asymmetric molecules that are non-super imposable mirror images of each other. |
Think of your hands |
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When can molecules have an optical isomer? |
If an atom (chiral centre) has four different groups attached to it. |
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What is the only difference in properties between optical isomers? |
The difference in the direction that they rotate plane polarised light in. |
This is why they are known as optical isomers |
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What is a racemic mixture? |
A 50:50 mixture of both optical isomers. |
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What is heterolytic fission? |
When the bond in a molecule is split so that both electrons remain with one of the atoms. |
Lysis means splitting |
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What is a nucleophile? |
An atom, group of atoms or ions which are attracted towards atoms with a positive or partial positive charge. |
They can donate and share electron pairs. |
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What type of reaction do monohaloalkanes undergo? |
Elimination or nucleophilic substitution. |
Think about the charge on the carbon in a haloalkane. |
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What is reacted with haloalkanes to make ethers? |
Alkoxide ions in ethanol |
It is made when alcohols react with alkali metals. |
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What is made when haloalkanes react with KOH dissolved in ethanol? |
An alkene |
It is an elimination reaction |
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How can haloalkanes be reacted to form carboxylic acids? |
React with cyanide (CN) negative ion in ethanol to make a nitrile which is then hydrolysed. |
There are two steps necessary |
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What is an SN2 reaction? |
Nucleophilic substitution involving two molecules in the rate determining step - it happens via a five-centred transition state. |
Two molecules involved |
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How can alcohols be made from alkenes? |
By reacting with acid-catalysed hydration reaction - addition of water. |
Alkenes undergo addition reactions |
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What is used to reduce aldehydes or ketones? |
Lithium aluminium hydride |
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Why do ethers have lower boiling points than isomeric alcohols? |
They cannot form hydrogen bonds between their molecule. |
Remember ethers have an O atom between carbon chains. |
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What could be used to dehydrate alcohols to form alkenes? |
Aluminium oxide, concentrated sulfuric acid or orthophosphoric acid |
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What is involved in the mechanism for addition of halogens to alkenes? |
Cyclic ion intermediate. |
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Which type of amines cannot form hydrogen bonds? |
Tertiary amines - they have 3 alkyl groups on the N atom. |
No N-H bonds |
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What type of reaction do aromatic compounds like benzene undergo? |
Electrophilic substitution. |
It is not addition |
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What is a drug? |
A substance which alters the biochemical processes in the body |
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What effect does an agonist drug have? |
It produces a response similar to the body’s natural active compound. |
It is opposite to antagonist drug |
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What do most drugs bind to? |
A receptor (usually protein molecules on the surface of cells or enzymes) |
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What does ppm stand for? |
Parts per million ( mg per kg or mg per litre) |
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