Types and Effects of Intermolecular Forces
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Intramolecular forces? 3 types?
forces WITHIN a molecule itself that keep a molecule together. 1) Metallic, 2) Ion-Ion, and 3) covalent network
Intermolecular forces?
Are forces that keep one molecule sticking to another molecule. The stronger the force, the more intensely molecules are attracted to each other
4 types of intermolecular forces?
1) ion-dipole 2) hydrogen bonding 3) dipole-dipole 4) dispersion forces (Van der Waals)
Ion-dipole Intermolecular force
intermolecularforce between ions and polar substances (NaCl in water)
hydrogen bonding intermolecular force
N-H, F-H, O-H bond in a pure substance
Dipole-dipole intermolecular force?
intermolecular force between POLAR non-ionic molecules that do NOT have an H bonded to O, N, or F
Dispersion Forces (or called London or van der Waals forces)
this is the intermolecular force between all molecules. Temporary dipole includes polar and nonpolar molecules. The greater the weight, the greater the London dispersion forces
list dipole-dipole, dispersion forces, and hydrogen bonding in order of increasing strength?
dispersion forces, dipole-dipole, hydrogen bonding, and ion-dipole
Can dispersion forces occur in individual atoms as well?
yes
If you have two molecules that only have dispersion forces, how do you know which one has more forces?
The larger molecule
If you have two molecules that only have dispersion forces, which one has a higher boiling point?
The larger molecule, bc the stronger the intermolecular force the higher the boiling point
All molecules have what type of intermolecular force?
dispersion forces
What is the weakest intermolecular force?
dispersion forces
strong IM forces indicate 4 properties?
1) high boiling point (high heat of vaporization) 2) high viscosity 3) high surface tension 4) low vapor pressure
viscosity
how thick a substance is. The thicker a substance, the more slowly it pours. Ex: molasses is more viscous than water
vapor pressure
upward pressure exerted by a substance on the atmosphere (or against atmospheric pressure)
When does boiling occur?
when the vapor pressure of a liquid substance equals or exceeds atmospheric pressure
IM forces and vapor pressure are directly or indirectly related?
indirectly
Would water boil faster on top of a mountain or in the grand canyon?
Top of a mountain. Bc atmospheric pressure decreases with higher altitude causing a lower boiling point
Why would vapor pressure decrease as boiling point increases?
If something has a high boiling point. that means it has a low vapor pressure bc it requires MORE HEAT to makes the vapor pressure high enough to allow boiling
what is atmospheric pressure at sea level?
1 atm. BP of water at sea level is 100 degrees C
Vapor pressure and boiling point are related how?
indirectly. higher vapor pressure=lower BP