Chemistry unit 2

Ionic Bonding

The electrostatic attraction between oppositely charged ions.

Giant Ionic Lattices

Have high melting points due to strong electrostatic forces between ions in all directions requiring a lot of energy to break.

Conductivity of Ionic Compounds

Ionic compounds conduct electricity only when molten or in solution, as the ions are free to move and carry charge.

Covalent Bonding

A shared pair of electrons between two non-metal atoms.

Simple Molecular Substances

Have low boiling points due to weak intermolecular forces which require little energy to break.

Diamond

Has a very high melting point because each carbon is covalently bonded to 4 others in a giant rigid lattice.

Graphite

Can conduct electricity because each carbon has 3 bonds and 1 delocalised electron free to move between layers.

Graphite's Softness

Is soft and slippery due to weak forces between layers allowing them to slide over each other.

Metallic Bonding

A giant lattice of positive metal ions surrounded by a sea of delocalised electrons.

Malleable Metals

Metals are malleable because the layers of ions can slide over each other without breaking the metallic bonds.

Nanoparticle

A particle between 1–100nm in size with a very high surface area to volume ratio.

Smart Material

A material that changes its properties in response to an external stimulus (temperature, light, etc.).

Thermochromic Pigment

Changes colour when the temperature changes.

Shape Memory Alloy

Returns to its original shape when heated.

Neutralisation Reaction

A reaction between H+ ions and OH- ions to form water (H2O).

Strong Acid

An acid that fully ionises/dissociates in water to release H+ ions.

Alkali

A soluble base that releases OH- (hydroxide) ions in water.

Hydrogen Gas Test

A lit splint makes a 'squeaky pop'.

Carbon Dioxide Test

Bubble through limewater; it turns cloudy/milky.

Methyl Orange

Is red in acid and yellow in alkali.

Phenolphthalein

Is colourless in acid and pink in alkali.

Soluble Salt from Insoluble Base

Made by adding excess base to acid, filtering the excess, evaporating water from filtrate, and crystallizing.

Ore

A rock containing enough metal compound to be worth extracting.

Reduction

The loss of oxygen.

Oxidation

The gain of oxygen.

Extraction of Less Reactive Metals

By reduction through heating with carbon.

Extraction of More Reactive Metals

By electrolysis.

Cryolite

Lowers the melting point of the electrolyte to save energy in Aluminium extraction.

Carbon Anodes Replacement

Must be replaced regularly because they react with oxygen to form CO2 and wear away.

Metal Formation Electrode

The metal is formed at the cathode (negative electrode).

Recycling Metals Benefits

Saves raw materials, uses less energy than extraction, reduces landfill.

Exothermic Reaction

A reaction that gives out heat energy to the surroundings (Temperature increases).

Endothermic Reaction

A reaction that takes in heat energy from the surroundings (Temperature decreases).

Activation Energy

The minimum energy required for a successful collision.

Bond Breaking

Is endothermic (requires energy).

Bond Making

Is exothermic (releases energy).

Energy Change Formula

Energy of bonds broken - Energy of bonds made.

Hydrocarbon

A compound containing hydrogen and carbon ONLY.

Fractional Distillation

The process used to separate crude oil based on boiling points.

General Formula for Alkanes

CnH2n+2.

General Formula for Alkenes

CnH2n.

General Formula for Alcohols

CnH2n+1OH.

Saturated vs Unsaturated

Saturated has only single C-C bonds; Unsaturated has at least one C=C double bond.

Alkenes Test

Add Bromine water; it turns from orange to colourless.

Isomers

Molecules with the same molecular formula but different structural formula.

Addition Polymerisation

Many small monomers (alkenes) join to form a long chain polymer.

Fermentation for Ethanol Pros

Uses renewable resources, low energy/cost.

Hydration of Ethene for Ethanol Pros

Fast reaction, produces very pure ethanol.

Dynamic Equilibrium

Forward and reverse reactions occur at the same rate in a closed system.

Haber Process Conditions

450°C, 200 atm pressure, Iron catalyst.

Haber Process Equation

N2 + 3H2 ⇌ 2NH3.

Haber Process Pressure Effect

Shifts equilibrium to the right (side with fewer moles) to increase yield.

Haber Process Temperature Effect

Shifts equilibrium to the left (endothermic direction) to decrease yield.

Contact Process Catalyst

Vanadium(V) Oxide (V2O5).

Sulfuric Acid Uses

Making fertilizers, detergents, and paints.

Flame Test for Lithium

Red.

Flame Test for Sodium

Yellow-Orange.

Flame Test for Potassium

Lilac.

Flame Test for Calcium

Brick-Red.

Flame Test for Barium

Apple-Green.

Halide Ion Test

Add Silver Nitrate solution.

Silver Nitrate Test Result for Chloride

White ppt.

Silver Nitrate Test Result for Bromide

Cream ppt.

Silver Nitrate Test Result for Iodide

Yellow ppt.

Moles Formula

Mass / Relative Atomic Mass (Ar or Mr).

% Yield Formula

(Actual Yield / Theoretical Yield) x 100.

Atom Economy Formula

(Mass of desired product / Total mass of reactants) x 100.