Chem ch 13 Flashcards
NON polar
hydrocarbons
3 important intermolecular forces between alkane (types of bonding)
dipole-dipole, hydrogen bonding, and london
dipole-dipole force (abba)
attraction between two partially opposite charged groups - aka - polar molecules ex. A-B and A-B (A positive and B negative)
stronger than dipole dipole
hydrogen bonding
hydrogen bonding (hydrogen bonds are FON)
when there is H and Oxygen, Nitrogen, Fluorine. H-O, H-N, H-F. hydrogen of one molecule and oxygen or nitrogen of another molecule
unique properties of H bonds
water has high boiling point, surface tension
london dispersion (away from london)
induced polarity - the only forces that non-polar molecules can form. Only intermolecular forces available in non-polar molecules, such as alkane
H-H bond is (type of bond and type of molecule)
nonpolar bond, AND it’s a nonpolar molecule
methane - CH4 - polar or nonpolar?
it’s nonpolar MOLECULE because the H is pulling evenly 4 ways. in methane, the BONDS are polar
strongest to weakest bonds
hydrogen, dipole-dipole, london
the stronger the bond…
the higher the boiling and melting point.
The more surface area, the higher the…
LDF
first 4 alkanes at room temp are…(4 different gases)
methane, ethane, propane, and butane - first 4 alkanes are gas (boiling point is below room temp)
5 - 15 alkanes at room temp are…(515 liquids)
liquid at room temp
combustion reaction
this is burning in oxygen. reason is to produce heat/ energy
formula for complete combustion of alkane
2CnH2n + (3n + 1) O2 - 2nCO2 + (2n +2) H20 (n is the number of the carbons - use the original number of carbons you start with)
halogenation reaction (just 2)
replacing hydrogen with halogens.
replacing h with either Cl or Br. - must be initiated by either heat or light (usually UV)
steps of holagenation (beginning to end)
- initiation, propagation, termination
initiation
radicals are formed by homolytic cleavage. bonds are broken down in such a way that 2 bonding electrons divide equally between the 2 atoms
how to name alkyl halide
find longest chain, identify parents, halogen, name main chain. - all the same but one - **drop ine and replace with 0
chiral carbon
not superimposable - called enatomers - connected with 4 different groups. /also called optical.
can hydrocarbons be dissolved in water?
usually not
intermolecular forces
forces holding electrons together
gases at room temp - polar or non?
non-polar
these are NOT called molecules
ionic compounds
even though sulfur (H2S) is lower on the periodic table, it has a lower boiling point…
than water - it should be higher bc the mass is more. Hydrogen bonding is really strong.
water boiling point
100 degrees celcius
alkane cannot make..(type of bond)
hydrogen bonding
alcohol can make…(type of bond)
hydrogen bonding
the only intermolecular forces that alkanes can form
london dispersion
H-H type of bond or CH4 - CH4
london dispersion - tug of war
increasing the size of the molecule increases the..
LDF and boiling point. ex. C2H6 has higher boiling point that CH4.
if given 2 molecules and asked which has the higher boiling point, choose..
the one that is a straight line. If it’s a cross shape for example, it’s more a pyramid and it has less surface area.
alkanes with 6 or more carbons…
waxy low melting point and solid
On test - if asked which has higher boiling point -
count # of carbon first, the larger will have a higher boiling point. IF they are the same, go with the surface area.
2 reactions of alkanes (C and H, just like alkanes)
combustion and halogenation
combustion - alkane + 02 =
CO2 and H2O + heat
if you don’t have enough oxygen during combustion, it produces…
CO2, carbon dioxide
2-headed arrow means..
2 electrons high to low concentration
1-headed arrow means..
1 electron high to low concentration
radical
are particles with 1 unpaired electron. they are formed by homolytic cleavage
homolytic cleavage
breaking down bond between 2 heads of the bond equally. the result is 2 particles called radicals. REMEMBER - each covalent bond has 2 electrons.
chlorine radical
a chlorine with 7 valence electrons, but 2 of them (bc there was a covalent bond that was broken)
very reactive
radicals
propagation
using 1 radical and the other one is formed with something
termination
when 2 radicals are being used, and there is no new radical for the formation. it’s over.
3 ways termination happens #1
if 2 Cl are just forming a bond, then there’s no radical, it’s just a bond.
3 ways termination happens #2
when Cl is added to methyl (CH3) radical BECAUSE it makes methane (chloromethane)
the purpose of the halogenation of methane is to..
replace all of the hydrogens
propagation starts with the..(on the left!)
reactants, then it uses the products
R-X means (rex hali)
alkyl halide. The R is the alkyl and X is the halide
when naming halides, drop the..
ine and replace with o. ex. chlorine is chloro. bromine is bromo, etc.
cycloalkane
just a circle
formula for cycloalkanes and cycloalkenes (coffee table)
CnH2n
cycloaklanes and cycloalkenes are..
constitutional isomers - same number of C and H.
simplest cycloalkane
C3H6 - this is cylcopropane
C3H6 (triangle shape)
cyclopropane (the triangle shape)
C4H8 (square shape)
cyclobutane
most stable cycloalkane is..
cylohexane - the bond angle is close to 109
C5H10 (pentagon shape)
cyclopentane
Dont confuse cyclohexane with benzene
they are both a hexagon, but benzene has the double bond every other carbon - it’s aromatic, not alphatic
if there is only one side chain on a cyclo, don’t put
the 1, the spot where the side chain intersects with the C
in cyclo, always give the number to the…
one with the side chain, if there’s only one
Don’t forget***if there are 2 side chains at the same carbon…
name it 1, 1 etc. or 2, 2 etc.
if there are 2 or more side chains in a cyclo, number it so…
the smallest numbers go the side chains
chiral carbons (on exam)
Just look for the carbon that is connected to 4 different groups - that’s it. rotate your hands
only switch the___and___with chiral carbons
right and left, not top and bottom
the 2 types of isomers
constitutional and stereoisomers
stereoisomers
same formula, same connectivity, different in orientation in space.
cis and trans are what type of isomers?
stereoisomers
trans
if the wedges and dashes are on different sides
cis
if there is one wedge on top, and one dash on top, or vice versa
saturated means ONLY (how many bonds?)
single bonds. never more than one bond
when counting carbons, also count the one on the..
side chain
