Chapter 10: Liquids and Solids

Molecular dipoles

center of mass of positive charge that does not coincide with the centers of mass of all negative charges (polar molecules have these)

Ion dipole forces

attraction between polar molecules and ions (anions are attracted to the positive end of polar molecules)

Dipole-dipole forces

weaker due to partial charges, molecules with permanent dipoles resulting from atoms with very different electronegativity

London dispersion forces

present in all atoms, electrons swish back and forth to form instantaneous dipoles wiht nuclei (more electrons = more polarizable = greater force)

Hydrogen bonding

a special case of dipole-dipole, have a higher boiling point (often between O- - - H and N- - -H)

Isomer

same formula, different arrangement of atoms

DNA

held together by hydrogen bonds (G to C, A to T)

Properties of liquids

adhesive, cohesive, surface tension, capillary action, viscosity

Adhesive

between liquid water molecules and the molecules on the surface of a container

Cohesive

forces that bind molecules of a substance together in bulk material

Surface tension

tendency of molecules @ the surface to be pulled inward due to an imbalance of IMF at the surface (higher when there are higher cohesive forces)

Capillary action

spontaneous rising of liquid in a narrow tube (adhesive property)

Viscosity

resistance to flow (cohesive property); pour quickly = low

Substitutional

one metal present in large % forms a lattice, some other metals for the points

Interstitial

one metal forms lattice, non-metal atoms in the interstices (ex. steel)

Molecular solids

soft, crumbly, weak IMF but have strong covalent bonds within them (ex. sugar or ice)

Covalent network

2D or 3D chains held together by covalent bonds between atoms

Silica

4 single bonds between silicon and oxygens in a covalent network (can be quartz or quartz glass)

Ionic

ions held together by ionic bonds

Metallic

bonding due to valence e- that are delocalized throughout the entire solid

Vapor pressure

partial pressure of vapor in dynamic equilibrium with the liquid (low = high boiling point, high = low boiling point)

Boiling point

temperature of vapor pressure of the liquid is equal to the external pressure

Melting point

temperature at which the liquid phase coexists with the solid phase

Normal boiling/ melting

external pressure is 1 atm

Fusion/ melting

solid to liquid

Vaporization

liquid to gas

Sublimation

solid to gas

Condensation

gas to liquid

Freezing

liquid to solid

Deposition

gas to solid

Boundary lines

both phases are present (equilibrium)

Triple point

all 3 phases are in equilibrium (only one on a diagram)

Critical point

no pressure can get the gas to liquify after this point