#intermolecular forces

[er-cryptid]

Vapor Pressure and Intermolecular Forces - Ex. 2

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[havealittlehappiness]

-Marcel

[phenolph-thalein]

Phenolphthalein, as you can probably tell my favourite molecule!

[a-studying-cactus]

10/100   Here's some notes on Intermolecular Forces for all of you! I'm finding Chemistry really conflicting. Some stuff is boring me on a molecular level and then some of it makes me really excited. It's weird since whenever I'm actually interested in it I remember it and then I have a bunch of content I keep having to go through because it just won't stick. Really want to do well on the exam though.

[studying-dreaming]

intermolecular forces

[chemicoolchemistry]

Electronegativity and Polarity

So basically, heres what you need to know for this quiz tomorrow. 

Electronegativity values are assigned values that measure the tendency of atoms and how they attract a bonded pair of electrons. 

To calculate the bond polarity of a molecule (determine if it is non polar covalent, or polar covalent) take the electronegativity values of each atom and subtract. This number will give you a decimal that lines up with the chart above, and determines whether it is nonpolar covalent or polar covalent (forget the moderately/very) 

To calculate the molecular polarity of a molecule, (determine if it is polar or non polar) it is helpful to look at the Lewis dot structure. If the structure is symmetrical (ex) H-H, then it is non polar. Lone pairs and longer formulas often signify that it is polar (asymmetrical) 

Helpful Notes:

Non polar bond 

-bonded electron shares are equal 

-EN values are from 0-0.39 

Polar Bond 

-bonded electrons are not shared equally between atoms 

-EN values from 0.4-1.7

Non Polar molecules 

-NOT attracted by electric field 

Polar Molecules

-called dipoles because they have separate regions of electron distribution within the cloud 

-attracted by electric field 

Partial Charge 

-delta represents positive charge (only polar covalent bonds!) 

-the more electronegative atom is at the negative end, while less-electro is at positive end 

-result is a dipole 

Intermolecular Forces 

-these forces relate to properties, such as hardness, boiling point, solubility, dipole, and volatility (tendency to vaporize) 

-covalent bonds are strong, but attraction between molecules are weak (aka LDF) 

a) London Dispersion Force 

    Vanderwaal Force 

   Induced Instantaneous Dipole  

-any type of force between non polar molecules (force is weak) 

      -weak force results in low melting/boiling points 

larger mass = bigger attraction and electron cloud 

larger LDF = higher boiling point 

***I don’t really understand the last part that I just wrote so pls just watch a Khan/Crash course on it 

[er-cryptid]

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[er-cryptid]

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