Covalent Bonding Flashcards
(24 cards)
Elements involved large complex molecules
H, C, N, O, P and S
What does the ability of an element to form chemical bonds depend on?
Electrons in the valence shell
Ne has the most stable valence shell
Properties of covalent bonds
- Strong
- Defined length
- Defined direction
- Define the stability and geometry of a molecule
Rotation around single bonds
- Changes conformation of the molecule (shape changes)
- Not all conformations are equally likely (energetically favourable)
- e.g. groups being close together is unfavourable and thus less likely
Trigonal planer vs Tetrahedral geometry
Trigonal planer has double bonds = no rotation
Tetrahedral has single bonds = allows rotation
Key feature of double bonds
Lie in a single plane
What are hydrocarbons?
CH groups
Importance of functional groups
Confer specific chemical properties and reactivity of a molecule
What are alcohols?
Have a single hydroxyl group (OH) at the end of the chain
What is an aldehyde?
Have an oxidised carbon (C=O) group at the end of the chain
What is a ketone?
Has an oxidised carbon (C=O) group in the middle
Difference between glucose and fructose
Glucose has an aldehyde group whereas fructose has a ketone group and then an alcohol attached to that
What can a carboxyl group be oxidised into?
Carbon dioxide
What groups become charged in neutral environments?
Amino groups (NH2) = positive
Phosphate groups = negative
How can esters be formed from a carboxylic acid?
Carboxylic acid reacts with a hydroxyl group to form an ester
How can esters be formed from a phosphate?
Phosphoric acid reacts with a hydroxyl group to form an ester
What is a phosphodiester?
Has 2 OH groups
What is an anhydride formed from?
2 carboxylic acids through condensation
Anhydrides are unstable in water
What are esters formed from?
An acid and alcohol through condensation
Formation of glycosidic bonds
2 hydroxyls react via condensation to form an ether
What are Acetals and Hemiacetals?
Acetals are when a glycosidic bond has been formed (O-R-O)
Hemiacetals are the oxidised version of the aldehyde form (O-RH-OH)
Amides and peptides bonds
Amino group (NH3+) and carboxyl group (C=O connected to O-) joined to make a polypeptide structure
An amide has a peptide bond (C=O-NH)
Importance of Cysteine
The only amino acid it’s a sulfhydride group (S-S)
Thiol groups
A sulfhydryl (thiol) group (SH) can form thioesters
A thioester bond is C=O connected to S
