2. Valence, Organic Compounds, Chemical Structures

Question 1

what are the electron capacities

Answer 1

2, 8, 18, 32
(2n^2)

Question 2

what is C’s valence, how do we tell?

Answer 2

4, column 14

Question 3

what is H’s valence, how do we tell

Answer 3

1, column 1

Question 4

why do we need to know about valence

Answer 4

it tells us how to element will bond, and how many bonds

Question 5

how many bonds can C form, why

Answer 5

4, because it has a valence of 4

Question 6

how many bonds can O form, why

Answer 6

2, because it has a valence of 6

Question 7

how many bonds can N form, why

Answer 7

3, because it has a valence of 5

Question 8

what is the most electronegative element

Answer 8

Flourine (F)

Question 9

what is polarity

Answer 9

a difference in electronegativity on either end of a bond that doesn’t cancel out

Question 10

why is Cl less electronegative than F when they’re in the same group

Answer 10

the electrons in Cl, because it has more, are further away from the bucleus so easier to break away relative to F

Question 11

what are the impacts of poalrity

Answer 11

• increases dissolubility in other polar compounds e.g. methane, water
• increase reaction with polar molecules
• increase boiling/melting point

Question 12

are steroid based hormones polar

Answer 12

no they’re non-polar

Question 13

polar and polar have the same relationships as non-polar and non-polar

Answer 13

yes (see impacts)

Question 14

what are the homologous series

Answer 14

alkanes –> one single bond only

alkenes –> at least one double bond

alkynes –> at least one triple bond

Question 15

which of the homologous series have higher melting points

Answer 15

alkynes

Question 16

what are the alkyl groups

Answer 16

branches off the main group

Question 17

what are the functional groups

Answer 17

alcohol -OH, chloro - Cl, carboxylic acid - CO, COH

Question 18

what are the rules for naming

Answer 18

1. homologous series - ane, ene, yne
2. longest C chain - meth, eth, prop, but, pent, hex etc.
3. alkyl groups - methyl, ethyl, propyl, butyl, etc (goes first)
4. functional groups (prefix)
   x = fluro, chloro, bromo, iodo
   OH = alcohol (-ol)
   NH2 = amino (-amine)

Question 19

what is hydrogen bonding

Answer 19

when an H attached to an N, O or F bonds with another H attached to an N, O or F. it is stronger than ion dipole, dipole dipole or London

Question 20

what does hydrogen bonding contribute to

Answer 20

it raises the BP of molecules e.g. OH raises the BP of alcohol. it also exists in vapour and controls the shape of molecules

Question 21

what does the longer chain in alkanes indicate for melting points

Answer 21

high melting points because CC and CH bonds are covalent not polar

Question 22

identify polarities/NP:
CC
CH
CN
OC
OH
NH
CX
CMgLi
CONR
CN

Answer 22

non polar
non polar
slightly polar
somewhat polar
all polar