Picking any two compounds, how do you describe which one has a higher dispersion force using the words Larger electron cloud and polarizability?
Thanks:)
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.
To determine which compound has a higher dispersion force, you can compare their electron clouds and their polarizability. Here's how you can do it:
1. Determine the size of the electron cloud: The larger the electron cloud, the stronger the dispersion force. This is because a larger electron cloud creates more temporary dipoles, leading to stronger attractions. You can compare the size of the electron cloud by looking at the molecular structure and the number of electrons in each compound.
2. Assess polarizability: Polarizability refers to how easily an electron cloud can be distorted by an external electric field. Compounds with more electrons or higher electron density tend to have greater polarizability. Since dispersion forces result from temporary dipoles, higher polarizability leads to stronger dispersion forces.
To compare the compounds using these concepts:
- Identify the compounds you want to compare.
- Assess the size of their electron clouds. Look at the molecular structure and the number of electrons in each compound. The compound with a larger electron cloud has a higher dispersion force.
- Evaluate the polarizability of each compound. Consider the number of electrons and the electron density. A compound with greater polarizability will have a higher dispersion force.
Remember that other intermolecular forces, such as dipole-dipole interactions and hydrogen bonding, can affect the overall strength of attractions between compounds. However, in this case, we are focusing specifically on dispersion forces.