Topic 1 - Key Concepts Flashcards
Chlorine Formula
Cl2
Ammonia formula
NH3
Ammonium ion
NH4+
Nitrate ion
NO3-
Sulfate ion
SO4 2-
Hydroxide
OH-
Carbonate ion
CO3 2-
Ionic equation
Symbol equation but spectator ions are removed
Hazard
Anything with the potential to cause harm
Risk
Is the probability of someone being harmed
Oxidising symbol
Provides oxygen which allows other materials to burn.
Harmful
‘!’ Cause irritation
Environmental hazard
Harmful to organisms and the environment
Toxic
Can cause death. By swallowing, breathing, contact.
Corrosive
Destroys materials including living tissue.
First atomic structure
John Dalton, everything is made up of solid spheres.
‘Plum pudding model’
JJ Thompson. Discovered charge and mass. He concluded there must be electrons.
Rutherford
Gold leaf experiment, concluded there is a positive nucleus surrounded by moving electrons.
Final atomic structure.
Bohr suggested energy levels with fixed orbits. Each shell has a fixed energy.
Relative mass of an electron
0.0005 (1/2000)
Relative atomic mass (Ar)
Average mass of one atom compared to the 1/12 of the mass of Carbon-12
Dmitri Mendeleev
Sorted into groups based on properties. He ordered using Atomic Mass. He left gaps for undiscovered elements and predicted their properties (ekasilicon and germanium). Tellurium and Iodine were the wrong way around.
Ionic Bonding
Metal and Non-metal react. Metal loses electrons forming a Cation. Non-metal gains electrons forming an anion. They are held together by electrostatic attraction.
Ionic lattice
Giant,crystalline, Strong electrostatic attraction in all directions.
Limitations of 2D representations (displayed formula)
Don’t show the shape or size of atoms.
Dot and cross diagrams limitations
Don’t show arrangement or size.
3D model limitations
Only show the outer layer of the substance.
Ball and stick limitations
Misleading with gaps between atoms where electrons interact, don’t show correct scale.
MP and BP of covalent substances
Low, as intermolecular are weak.
As molecules get bigger their..
Intermolecular forces require more energy to break them.
Giant covalent properties
Strong Covalent bonds.
Very high MP and BP.
Don’t conduct.
Insoluble.
Diamond
Each carbon is bonded 4 times. Require lots of energy to break bonds. Rigid lattice making it very hard. Can’t conduct.
Graphite
Each carbon bonded 3-times. The extra electron is delocalised making it conductive. Layers can move making it a good lubricant.
Graphene
A single layer of graphite.
Sheet of carbon hexagons.
One atom thick, 2D.
Fullerenes
Form molecules of carbon shaped in tubes or balls. Made up of carbon Hexagons (sometimes pentagons and heptagon).
Uses of Fullerenes
- Delivering drugs to cells. ‘Cage’ other molecules.
- Very large surface area used for industrial catalysts as molecules can be attached to them.
- Nanotubes can be used (graphene cylinders) to strength materials as they’re strong and light
If mass increases
Reactant was a gas
If mass decreases
Product is a gas.
Find molecular formula from empirical formula
Find Mr of empirical formula.
Mr of compound / Mr of empirical formula
Multiply empirical formula
Moles =
Mass
Mr
Avogadro’s constant
6.02 x 10^23
Concentration
Mass / volume
1dm^3
1000cm^3
Empirical formula experiments.
Weigh crucible.
Add magnesium, weigh again, subtract from original to calculate the mass.
Heat the crucible with lid (preventing bits escaping) until all ribbon has turned white.
Cool and reweigh crucible with contents. Calculate the mass of magnesium oxide. Calculate moles of added oxygen and original magnesium.
Limiting reactant
The reaction stops once one of the reactants have been used up.
Amount of product ∝ limiting reactant.
Find balance equation from masses
Calculate the number of moles
Divide through by the lowest number of moles.
Make it integer. Put into equation.
