DAT chem 5 - Liquids and solids

intramolecular forces examples

metallic

ionic

covalent

intermolecular forces

ion dipole

Hydrogen

dipole dipole

dispersion

What does hydrogen bonding apply to

molecules that have H bonded to NOF

Dipole dipole forces

non covalent molecules that dont have H bonded to NOF

What leads to a molecule having more LDF

its size

What do strong intermolecular forces lead to

High boiling point

high viscocity

high surface tension

high heat of vaporization

low vapor pressure

Vapor pressure

the molecules on top of a liquid push down on it. The liquid pushes back. Once the forces are the same, the liquid boils.

So, we can assume that water has a low vapor pressure, as its boiling point is high. It doesnt want to boil, therfore keeping its vapor pressure low

Metallic solids

held togehter by a sea of electrons, allwoing for electricity conductivity, stong but not brittle

Ionic solids

held together by a strong attractions between cations and anions.

do not conduct electricity and are brittle

Covalent networ solids

held together by an extended network of covalent bonds, very hard

Give semiconductors their properties

Molecular solids

held together by IM forces

soft with low melting points

unit cell

if you zoom in ona crystalline solid closely enough, you would see that the entire solid is comprised of a small repeating unit called a unit cell

Simple cubic

only one atom in the cell 1/8

Body centered cubic

2 cells

1/8×8 +1

Face centered cubic

4 cells

(1/8*8) + (½ *6)

Deposition

Gas into solid

Fusion

melting

crystallization

Freezing

Sublimation

Solid into gas

Phase changes entropy and energentics

Boilijng point and vapor pressure relationship

Higher boiling point, lower vapor pressure

phase diagram

bottom is gas

left is solid

right is liquid

Y axis is pressure

x axis is temp

phase diagram Lines

where the two phases coexist

phase diagram critical point

where liquids and gasses are indestinguishable

triple point

all three phases exist in equilibrium

Whats unique about the phase diagram of water

For most molecules on earth, the solid is more dense than the liquid.

meaning, as pressure increases, The gas will turn into a solid, which will then turn into a liquid, which will turn into a solid

Water is different though, as its liquid form is more dense. This in turn means that upon adding more pressure, the solid fuses into liquid.

This turns its phase chart into a negative slope