1What are intermolecular forces?
Forces of attraction between molecules.
2How do intermolecular forces compare to covalent bonds?
They are much weaker.
3What are the three types of intermolecular forces?
Instantaneous dipole-induced dipole (London), permanent dipole-dipole, hydrogen bonding.
4What causes instantaneous dipole-induced dipole forces?
Random movement of electrons creating temporary dipoles.
5What affects the strength of London dispersion forces?
Number of electrons and surface area of the molecule.
6Which has stronger London forces: pentane or neopentane?
Pentane, due to greater surface contact.
7What is a permanent dipole?
A dipole that does not change due to asymmetrical electron distribution in polar bonds.
8What causes permanent dipole-dipole forces?
Attraction between molecules with permanent dipoles.
9What is a hydrogen bond?
An intermolecular force between a hydrogen atom bonded to N, O, or F and a lone pair on N, O, or F in another molecule.
10What elements are involved in hydrogen bonding?
Nitrogen, oxygen, and fluorine.
11What are the conditions for hydrogen bonding?
Hydrogen bonded to N, O, or F; a lone pair on N, O, or F in another molecule.
12Why is ice less dense than water?
Hydrogen bonding causes an open lattice structure in ice.
13Why does H₂O have a higher boiling point than H₂S?
Due to hydrogen bonding in water.
14What happens to boiling points down Group 7 hydrides?
They increase due to stronger London forces.
15Why is the boiling point of NH₃ higher than PH₃?
NH₃ has hydrogen bonding, PH₃ does not.
16What types of substances are soluble in water?
Polar substances and those that form hydrogen bonds.
17Why do non-polar molecules not dissolve well in water?
They cannot form hydrogen bonds with water.
18What affects the solubility of alcohols in water?
Length of hydrocarbon chain and presence of -OH group.
19Why are long-chain alcohols less soluble?
The non-polar chain disrupts hydrogen bonding with water.
20Why does ethanol dissolve in water?
It forms hydrogen bonds with water molecules.
21Why do molecules with similar IMF mix?
They form similar interactions, increasing entropy.
22Why does oil not mix with water?
Oil has London forces; water has hydrogen bonds—different IMFs.
23What determines the boiling point of a substance?
Type and strength of intermolecular forces.