YR 11 CHEM Term 3 Assessment - Prelims Content

Boyle’s Law

P1V1=P2V2
Pressure is inversely proportional to volume

Charle’s Law

V1/T1=V2/T2

Direct relationship between volume and absolute temeprature

Gay Lussac Law

P1/T1=P2/T2

Direct relationship between pressure and absolute temperature

Avogadro’s Law

V1/n1=V2/n2

Direct relationship between volume and moles

Combined gas law

(P1V1)/T1=(P2V2)/T2

Compares one gas at two states

Ideal gas law

PV=nRT
(T is Kelvin, kPa, litres, R=8.314)

Pure substance

fixed composition/properties, can't be separated by physical means

Mixture

– variable composition, can be separated physically

Element

– simplest pure substance, one type of atom

Compound

– 2+ elements chemically bonded, fixed ratio

Homogeneous mixture

uniform composition throughout

Heterogeneous mixture

– composition varies, parts visibly different

Solution

homogeneous mixture, particles too small to see/settle

Solute and solvent

Solute = substance being dissolved

Solvent - dissolving

Suspension

heterogeneous, particles settle over time

Colloid

small particle clusters, evenly dispersed, doesn't settle

Miscible

liquids that mix completely

Sieving

separates SOLIDS (solid from solid) by particle size

Filtration

separates insoluble solid from liquid (solid stays on paper, liquid passes through)

Sedimentation and decantation

solid settles to bottom of container (then pour out non solid liquid)
process of carefully pouring out liquid leaving solid

Evaporation

vaporises liquid (low bp), leaves solid residue (used for dissolved solids)

Distillation

boils + condenses liquid to separate from mixture; big difference in boiling points needed

Fractional distillation

separates miscible liquids with close boiling points (<40–50°C apart), e.g. crude oil, ethanol from fermentation

Separating funnel

separates immiscible liquids by density (layers)

Solvent separation (dissolve + filter)

dissolves one component, filters off insoluble, evaporates solvent to recover soluble solid

Gas separation

uses differences in boiling point or solubility in water

Ionic (structure, solubility, conductivity, hardness, brittleness, density)

• Structure – lattice of alternating +/– ions, held by strong electrostatic forces of attraction (efa)

• Solubility – usually soluble in water; water molecules pull ions apart (solute-solvent attraction beats lattice attraction)

• Conductivity – does NOT conduct as solid (ions fixed in place); DOES conduct when molten or dissolved (ions free to move and carry charge)

• MP/BP – high; strong efa between ions needs lots of energy to break

• Hardness – hard; strong efa holds ions firmly in place

• Brittle – yes, brittle; force shifts lattice, lines up like charges, they repel and crystal shatters

• Density – generally high; ions packed tightly in a rigid lattice

Covalent molecular (structure, solubility, conductivity, hardness, brittleness, density)

• Structure – small molecules, strong covalent bonds within each molecule, weak intermolecular forces (imf) between molecules

• Solubility – often insoluble/variable; depends on whether solute-solvent forces can overcome the weak imf

• Conductivity – does NOT conduct (no ions or free electrons available)

• MP/BP – low; only weak imf need breaking (covalent bonds within molecule stay intact)

• Hardness – soft; weak imf lets molecules slide apart easily

• Brittle – NOT brittle; molecules just separate, or substance is already liquid/gas

covalent network (structure, solubility, conductivity, hardness, brittleness, density)

Covalent Network (e.g. Diamond, SiO₂)

• Structure – giant 3D network, every atom covalently bonded to neighbours

• Solubility – insoluble; would require breaking strong covalent bonds

• Conductivity – does NOT conduct (all electrons locked in covalent bonds, none free)

• MP/BP – very high; strong covalent bonds throughout entire structure must be broken

• Hardness – very hard; rigid strong-bonded network

• Brittle – NOT brittle; resists deformation entirely rather than sliding

Metal (structure, solubility, conductivity, hardness, brittleness, density)

Metallic (e.g. Mg, Cu, Fe)

• Structure – lattice of positive metal ions surrounded by a "sea" of delocalised (free-moving) electrons

• Solubility – insoluble; no solvent can overcome metallic bonding

• Conductivity – DOES conduct, in both solid and molten state; delocalised electrons are free to move and carry charge

• MP/BP – high; strong efa between positive ions and delocalised electron sea

• Hardness – hard; strong attraction throughout electron sea

• Brittle – NOT brittle; malleable/ductile — layers of ions slide over each other while electron sea keeps attracting them, so it bends rather than shatters

Element notation with mass number and atomic number

Stability of isotopes

n:p ratio
Stable light element (Z:1-20) - 1:1

Stable heavy elements (Z:73-83) - 1.5:1

Radioactive particle emmissions

(for beta, neutron is turned into proton which stays and electron)

Reactivity series

what technique to use to separate what

• Particle size → sieving

• Solid vs liquid → filtration

• Big bp difference → distillation

• Small bp difference → fractional distillation

• Soluble vs insoluble → solvent + filtration

• Immiscible liquids → separating funnel

Polyatomic ions