Picking any two compounds, how do you describe which one has a higher dispersion force using the words Larger electron cloud and polarizability?
Thanks:)
2 answers
I THINK you need to look at the molecular weight of the 2 compounds. I have not had formal chemistry learnin' since the day the people came to tha place where the lab speraments wuz hapenin'! Seriously though- consider the make-up of the compound and its components electrons in the outer ring of each molecule. Polarization would have to follow the same theory, as the mass of a molecule is determined by its' # of protons and neutrons in the nucleus. It would stand to reason that a molecule with an equal charge between the nucleus and the rings of electrons it has would be neutral as far as polarization, the inverse would be true if the charges did not cancel. Think of the Noble Gases.
The molar mass is an indirect relection of the polarizablity. Because molecules with higher molar masses often have more protons and thus more electrons the molecule will be more suseptable to polarizablity.
Polarizing a molecule is deforming its electron cloud. Some molecules have slight defomrations build into them like H2O where it is only slightly polar and the electrons are concentrated near the oxygen, or comepletely polar as in the ionicly bound NaCl, or comepletely non-polar like CCl4 (carbon tetrachloride).
Water (and carbon tetrachloride) is held together by the weak inbalances in the charge distrubution of their electron clouds. Water is the easiest to visualize with the negativly (electron rich) charged oxygen being attracted to the positive (electron poor) charged hydrogen of a different molecule.
In Carbon Tetrachloride things a slightly different. An individual molecule has a uniformly distributed cloud of electrons but when another molecule is placed near it, the two electrong clouds with repel each other allowing for a dipole moment to arise which will result in the weak london dispersion forces.
Polarizing a molecule is deforming its electron cloud. Some molecules have slight defomrations build into them like H2O where it is only slightly polar and the electrons are concentrated near the oxygen, or comepletely polar as in the ionicly bound NaCl, or comepletely non-polar like CCl4 (carbon tetrachloride).
Water (and carbon tetrachloride) is held together by the weak inbalances in the charge distrubution of their electron clouds. Water is the easiest to visualize with the negativly (electron rich) charged oxygen being attracted to the positive (electron poor) charged hydrogen of a different molecule.
In Carbon Tetrachloride things a slightly different. An individual molecule has a uniformly distributed cloud of electrons but when another molecule is placed near it, the two electrong clouds with repel each other allowing for a dipole moment to arise which will result in the weak london dispersion forces.
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