Dispersion forces and other bonds. (1 Viewer)

[blieu]

Someone tell me everything they know about bonds esp. dispersion forces. I really suck at them and I know it's prelim stuff but I forget prelim shit.

 

[Merase]

http://community.boredofstudies.org/showthread.php?t=284599 and ctrl + f to "Intermolecular forces fall into two categories"

+ http://www.ausetute.com.au/intermof.html for further reading. Realised the holes of information in the prior link. =_=

 

[cineti970128]

According to my theory note

Metallic bonds:
occcur in metals where they hold the positive metal ions together. the meatallic bonds are caused by the radom motion of the delocalised outer shell electrons of metal atoms and their attractin to the positive ions.

Ionic Bonds:
they hold positicely charged metal ions together with negatively charged non-metal ions. it is caused by the electrostatic attraction between oppositely charged ions.

Covalent Bonds
sharing of one or more pair of electrons


INTERMOLECULAR FORCE
Intermolecular force is attractive forces between molecules. It can be:
1.dispersion force
2. dipole - dipole force
3. hydrogen bonds

Dispersion Forces are weak attractive forces between all molecules due to random movements of electrons around molecules forming momentary charge

Dipole Dipole Force are stronger attractive forces between polar molecules.
greater the polarity = greater dipole dipole force

Hydrogen Bond is a special form of dipole dipole force where electrostatic attractions occurs between H+ of an molecule and a highly electronegative atom (O, N, F) of another molecule


Remember Solubility is related to this intermolecular force
For a substance to dissolve -Dissolution is when intermolecular force in each solvent and solute break allowing solute to dissolve
Weak dispersion force = less dissolution

example Oxygen has weak dispersion force
therefore when air bubbled through water,
the attraction is weak
oxygen is not very soluble


Ethanol has dipole dipole bonds and covalent bonds
therefore can dissolve ionic substances and also covalent substances = excellent solvent

correct me if iam wrong hope it helps

 

[someth1ng]

Hydrogen Bond is a special form of dipole dipole force where electrostatic attractions occurs between H+ of an molecule and a highly electronegative atom (O, N, F) of another molecule


Remember Solubility is related to this intermolecular force
For a substance to dissolve -Dissolution is when intermolecular force in each solvent and solute break allowing solute to dissolve
Weak dispersion force = less dissolution

example Oxygen has weak dispersion force
therefore when air bubbled through water,
the attraction is weak
oxygen is not very soluble

Ethanol has dipole dipole bonds and covalent bonds
therefore can dissolve ionic substances and also covalent substances = excellent solvent

Remember that in hydrogen bonding, it is the intermolecular force between a hydrogen that is physically bonded to a highly electronegative atom to another intermolecular, highly electronegative atom (N,O,F)
Example: N-H...F

Solubility depends on the polarity of a molecule and that "like dissolved like". That is, a polar substance can dissolve in a polar substance and a non-polar substance can dissolve in a non-polar substance. The strength of the intermolecular force is related to boiling and melting points. Ionic compounds are not quite polar since each ion as a single charge but it is not non-polar either - in these cases, dipole-ion bonds are formed which are even stronger than hydrogen bonding. If the electrostatic force holding an ionic compound together as a solid is more powerful than the dipole-ion bond formed between the solvent and the ion, then it will be mostly insoluble.

Oxygen (O2) is mostly insoluble in water because it is non-polar, however, due to the size of the oxygen molecule, it is able to fit in between the H2O molecules in water to be slightly soluble.

Ethanol is a good solvent because it contains both a non-polar alkyl chain and a polar hydroxyl functional group. The alkyl group allows non-polar solutes to be dissolved in ethanol including hydrocarbons while the polar hydroxy group allows dipole-dipole, dipole-ion and hydrogen bonds to form. Because ethanol is miscible and can dissolve both polar and non-polar substances, it is an exceptional solvent.

 

[cineti970128]

very gud !
cheers
n btw where did u learn all this?
from which textbook if u r using one?
I just use dot point

 

[someth1ng]

very gud !
cheers
n btw where did u learn all this?
from which textbook if u r using one?
I just use dot point

I use some state rank notes (courtesy of Kamal for giving them to me) and occasionally chemistry context as well as conquering chemistry.