PHASES OF MATTER
density, = mass per unit volume
ρ = m/V [kg/m³]
homogeneous sub: uniform density throughout subs
temp & pressure affect density
gas; temp & pressure- large
liquid; temp affects density more than pressure
solid; temp & pressure- little affect

Solids
-definite vol + shape
-atoms vibrate about mean position (vibn small compared to atom sepn)
-atoms arranged regularly & closely over long dist
-short range attractive F, v.short range repulsive force (if no repulsion > structure collapses)
density: generally high (atoms packed tightly & closely)

Liquids
-definite vol + indefinite shape
-atoms flow and move abt randomly & freely (don't maintain contact w/ other atoms)
-atoms arranged regularly over close dist (attractive F)
density: generally high, but less than solid (atoms packed closely like solid but spaced out a bit)

Gases
-indefinite vol + shape
-atoms move abt randomly & freely (v.little attractive F)(ideal- no F)
-atoms randomly arranged, spread out
density: very low (atoms far apart)

Brownian motion
-random movement of smoke particles in a smoke cell (due to random bombardment of air molecules)
-proves molecules (air) are moving continuously & randomly

Crystalline structure: atoms repeatedly arranged regularly over long dist (atoms in fixed, lattice, positions) (like solids)
-mostly solids, metals, minerals
Amorphous structure: atoms arranged regularly over short dist (like liquids but less mobile) (glass)

Metals
-crystalline [actually polycrystalline- many crystals/ grains, that pt in diff dirns (under controlled cond > flawless structure = whiskers)]
-atoms arranged in order way
-positive metal ions in a sea of electrons (ions pull electrons > close-packed structure)

Polymers
giant chain-like molecules formed from monomers (small, basic unit) > each molecule 1000's/10⁶'s atoms
amorphous polymers: chains tangled (molecules irregularly arranged, no long range molecule order)
semi-crystalline polymers: chains arranged properly (have well-ordered crystalline regions)

Pressure,p = normal F per unit area,A
av.pressure = total F / total area, A
pressure at pt, p = δF/δA [pa: pascal]
1 pa = pressure of 1N per square metre
pressure due to gas molecules bombarding w/ walls
-assume elastic collision
-molecules hit wall > change dirn > change momentum > F on molecule (F = dp/dt) > molecule exerts F on wall (Newton's 3rd law) > dp/dt ÷ area = pressure

Melting (solid > liquid) (only at mp)
specific latent heat of fusion: energy required to change unit mass of subs from solid phase to liquid phase
specific latent heat of fusion absorbed during melting > no heat change at mp (latent heat: used to break bonds)

Boiling (liquid > gas) (only at bp)
bp = temp at which saturated vapour pressure = external pressure on surface (> bp depends on ext pressure)
specific latent heat of vaporisation: energy required to change unit mass of subs from liquid phase to gas phase (latent heat)
specific latent heat of vaporisation absorbed during boiling > no heat change at bp
lh of vapn larger than lh of fusion as lh of vapn needs to separate molecules st no / v.litte attraction bet molecules (in gas phase) & also needs to expand gas against atm pressure (gas vol much greater than liquid)

Evaporation (liquid > gas)
-process where more energetic liqiud molecules escape from surface of liquid and turn into gaseous state (occurs at any temp)
-causes a cooling effec