Gizmo

• Allotrope


  Different structural forms of the same element in the same physical state
• Allotropes of carbon


  • Diamond
  • Graphite
  • Fullerenes
• Diamond


  • Giant covalent structure
  • Each carbon atom is covalently bonded to 4 carbon atoms
  • Strong
  • High melting point
  • Don't conduct electricity as there is no free electrons
• Graphite


  • Giant covalent structure
  • Each carbon atom is covalently bonded to 3 other carbon atoms
  • Soft
  • High melting point
  • Able to conduct electricity because each carbon atom has one delocalised electron
• Graphene


  Single layer of graphite
• Fullerene


  Graphene scientifically modified into different structure
• Graphite has weak intermolecular forces meaning layers can slide over each other, making it soft and brittle
• Buckminster's first spherical fullerene = C60
• Alloy


  Mixture of metallic solution
• Ar


  Relative atomic mass (average mass of all isotopes)
• Mr


  Relative formula mass (Ar + Ar)
• MgCl2 has a relative formula mass of 95
• The percentage mass of oxygen in Calcium hydroxide, Ca(OH)2, is 54%
• Number of moles


  Mass (g) / Relative formula mass (Mr)
• Ammonia, NH3, has a relative formula mass of 17
• Limiting reactant


  Reactant which gets used up and stops the chemical reaction
• 4 Na = 5 moles, so 2 Na = 2.5 moles and the mass = moles (2.5) x Mr (23) = 57.5g
• Acid


  pH less than 7
• Base


  pH greater than 7
• Strong acids


  • Completely ionize, so all acid particles dissociate to release hydrogen ions/turn into products completely
• Weak acids


  • Don't fully ionize; only a few acid particles dissociate to release hydrogen ions
• As pH decreases by 1


  Hydrogen ions increase by 10x
• Neutralisation reaction


  Acid + base, hydrogen ions react with hydroxide ions
• Group 1 elements are the most reactive
• Displacement reactions


  More reactive metals can displace less reactive ones
• Magnesium can displace copper, but copper cannot displace iron
• Metal + acid


  Salt + hydrogen
• Sodium hydroxide releases hydrogen gas when it reacts
• Reduction


  Gaining of hydrogen
• Extracting pure metals from metal oxides


  Using carbon, which causes the metal to lose its oxygen, producing CO2
• This process only works for metals less reactive than carbon
• Pure gold is found in the ground as it is unreactive
• Iron is not found pure in the ground as it is reactive enough to react with oxygen and form iron oxide
• Redox reactions


  Oxidation (loss of electrons) and reduction (gain of electrons) happening at the same time
• Electrolyte


  Liquid that contains an ionic compound
• Equipment needed for electrolysis

  1. Beaker with electrolyte

  2. Electrodes (anode and cathode)

  3. Wires and battery to connect electrodes
• Anode


  Positive electrode
• Cathode


  Negative electrode
• Electrolysis


  1. Negative ions attracted to anode and discharged

  2. Positive ions attracted to cathode and discharged
• Anode oxidises, cathode reduces