2. Valence, Organic Compounds, Chemical Structures Flashcards
what are the electron capacities
2, 8, 18, 32
(2n^2)
what is C’s valence, how do we tell?
4, column 14
what is H’s valence, how do we tell
1, column 1
why do we need to know about valence
it tells us how to element will bond, and how many bonds
how many bonds can C form, why
4, because it has a valence of 4
how many bonds can O form, why
2, because it has a valence of 6
how many bonds can N form, why
3, because it has a valence of 5
what is the most electronegative element
Flourine (F)
what is polarity
a difference in electronegativity on either end of a bond that doesn’t cancel out
why is Cl less electronegative than F when they’re in the same group
the electrons in Cl, because it has more, are further away from the bucleus so easier to break away relative to F
what are the impacts of poalrity
- increases dissolubility in other polar compounds e.g. methane, water
- increase reaction with polar molecules
- increase boiling/melting point
are steroid based hormones polar
no they’re non-polar
polar and polar have the same relationships as non-polar and non-polar
yes (see impacts)
what are the homologous series
alkanes –> one single bond only
alkenes –> at least one double bond
alkynes –> at least one triple bond
which of the homologous series have higher melting points
alkynes
what are the alkyl groups
branches off the main group
what are the functional groups
alcohol -OH, chloro - Cl, carboxylic acid - CO, COH
what are the rules for naming
- homologous series - ane, ene, yne
- longest C chain - meth, eth, prop, but, pent, hex etc.
- alkyl groups - methyl, ethyl, propyl, butyl, etc (goes first)
- functional groups (prefix)
x = fluro, chloro, bromo, iodo
OH = alcohol (-ol)
NH2 = amino (-amine)
what is hydrogen bonding
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
what does hydrogen bonding contribute to
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
what does the longer chain in alkanes indicate for melting points
high melting points because CC and CH bonds are covalent not polar
identify polarities/NP:
CC
CH
CN
OC
OH
NH
CX
CMgLi
CONR
CN
non polar
non polar
slightly polar
somewhat polar
all polar
