OZ 7 The ozone hole

What is the strongest type of intermolecular bond?

hydrogen bond

What 3 features must molecules have for hydrogen bonding?

1. large dipole between H atoms and highly electronegative atom such as O, N, F

2. small hydrogen atom which can get very close to O, N or F atom in nearby molecule

3. lone pair of electrons on O, N, F that positive H can line up with

Electronegativity of halogen ____________ down the group

decreases

viscosity

measure of how easily a liquid flows

Liquids with hydrogen bonding have _____ viscosity

high

Why are substances with hydrogen bonding soluble in water?

hydrogen bonds form between water and substance molecules

substance dissolves

Why does HF have a higher boiling point than HCl, HBr, or HI?

Strong hydrogen bonding in HF

increases intermolecular forces

Why can water form more hydrogen bonds than hydrogen fluoride?

Water has two lone pairs on oxygen

each molecule forms two hydrogen bonds.

How does hydrogen bonding affect viscosity?

Stronger hydrogen bonds increase viscosity

harder for molecules to flow past each other

How does viscosity change with temperature in hydrogen-bonded liquids?

As temperature increases, hydrogen bonds break more easily,

reducing viscosity.

Why does water dissolve many substances?

Water is polar and forms hydrogen bonds with other polar molecules and ions,

Why don’t non-polar substances dissolve well in water?

cannot form hydrogen bonds

water molecules remain strongly attracted to each other