Drug discovery 6a

Question 0

what is the atomic mass?

Answer 0

number of protons + number of neutrons

Question 1

what is the atomic number ?

Answer 1

number of protons in the nucleus

Question 2

what are the number of protons equal to in an atom?

Answer 2

number of electrons

Question 3

what do the atomic number and molecular mass enable ?

Answer 3

enable a schematic drawing of an atom to be produced

Question 4

what are radioactive isotopes used for ?

Answer 4

to label ligands for binding assays

Question 5

how are electrons organised in an atom ?

Answer 5

they are organised into electron shells

• each level down an additional shell is added
• first shell only contains 2 electrons while 2nd and 3rd can contain 8
• electrons only occupy the next shell once the previous one has become full

Question 6

atoms prefer to have a full electron shell so what does this mean ?

Answer 6

it means if they dont have a full electron shell they will either donate or share electrons
atoms are more stable when they have a full outer shell of electrons - therefore group 8 elements are notoriously stable, unreactive

Question 7

when is formed when atoms donate or accept electrons ?

Answer 7

ionic bonding

Question 8

what is covalent bonding ?

Answer 8

it is the sharing of electrons to form full outer electron shells

Question 9

what are lone pairs?

Answer 9

electron pairs that remain unshared in a molecules

Question 10

what do lone pairs cause?

Answer 10

they are important for defining the shape of the molecule and also forming electrostatic interactions

Question 11

what is the bond angle between the hydrogen atoms in methane and what shape is this molecule?

Answer 11

109.5 degrees
produces a tetrahedral shape around the central atom - this is an ideal shape but it can vary in non-symmetrical molecules like water

Question 12

what is the bond angle between the hydrogen atoms in water ?

Answer 12

104.5 degrees

Question 13

what do lone pairs that are next to each other do ?

Answer 13

they repel each other

Question 14

how many outer electrons does a nitrogen atom have and what does this mean ?

Answer 14

it have 5 outer shell electrons

shares 3 of them to produce 1 lone pair

Question 15

what shape is a benzene molecule ?

Answer 15

planar

Question 16

what property does a cyclohexane ring have ?

Answer 16

it is puckered

- forms a chair or boat conformation

Question 17

what happens in covalent double bonding ?

Answer 17

atoms share 2 electrons

Question 18

what shape is ethene and what is the bond angle?

Answer 18

flat/planar shape- trigonal planar

120 degree bond angle

Question 19

what is the difference between a single covalent bond and a double covalent bond ?

Answer 19

double covalent bonds do not spin they are fixed

Question 20

what is characteristic of the benzene ring ?

Answer 20

there are 3 double covalent bonds in the ring

the electrons in the 3 double bonds are shared across all 6 bonds in the ring = delocalisation

Question 21

what structures are common in drug structure ?

Answer 21

aromatic rings

Question 22

what is electronegativity ?

Answer 22

it is the attraction of an atom for electrons

- some atoms have a very high attraction for electrons e.g. F, O, N = high electronegativity

Question 23

if there is a large difference in electronegativity between 2 atoms what forms ?

Answer 23

ionic bond

Question 24

if there is a small difference in electronegativity between 2 atoms what is formed ?

Answer 24

a covalent bond

Question 25

what is formed if there is an intermediate difference in electronegativity ?

Answer 25

polar covalent bond formed

- the electronegative atom pulls the shared electrons closer to itself giving itself a partial negative charge

Question 26

what is a polar molecule ?

Answer 26

a molecule that has one end more polar than the other

Question 27

why is carbon dioxide non-polar ?

Answer 27

even though it has 2 polar bonds it doesnt have a dipole because their polarities cancel each other out

Question 28

what do polar molecules prefer to interact with and what does this cause ?

Answer 28

prefer to interact with polar molecules
- therefore tend to separate leaving the non-polar molecules to interact with each other by weak van der waals interactions

Question 29

what is a hydrogen bond ?

Answer 29

it is the interaction of the hydrogen on one molecule to O or N or F that is attracted to an O or N or F of a different molecule

Question 30

what are the different types of isomers ?

Answer 30

structural isomers 
geometric isomers 
stereo isomers (enantiomers)

Question 31

what are isomers ?

Answer 31

different molecules that contain the same atoms but in a different arrangment

Question 32

what are structural isomers ?

Answer 32

same atoms but different arrangement in space

Question 33

what are geometric isomers ?

Answer 33

same molecular formula but different arrangement due to a double bond

• cis and trans isomers
• cis= atoms on same side
• trans= atoms on opposite side

Question 34

what are stereo isomers ?

Answer 34

same molecular formula but mirror images of each other (non-super imposable)

Question 35

what is a chiral carbon ?

Answer 35

a carbon atom that has 4 different groups attached to it

it is a chiral centre

Question 36

what are stereo isomers important for ?

Answer 36

important in molecular recognition