Past paper mistakes

• Explain how the potential difference across the resistance and the lamp will change when the switch is closed

  The resistance- the potential difference across the resistance become 0V because there is a short circuit across the resistor

  The lamp - the potential difference across the lamp increases because the current increases
• Explains how motion of air molecules caused tje pressure in tje container to chnage as the temperature decreased

  Pressure drescrese because molecules have less kinetic energy so fewer colliosn with the wall
• How did increasing the resistance affect the current in the circuit

  Current decrease
• Whta happens when thermometer temp increase

  Increase of temperature of thermometer the current increase because resistance decscreas
• What happesn when resistance increase

  Current decrease
• Electrolysis

  only ionic compound
• What are the properties of graphite 


  One atom thick

  Delocailsed electron which is useful in electronic

  Strong hexagonal structure for strong intermolecular forces
• Properties for fullerenes 


  Hallow structure useful for delivering drugs to cells

  Conduct electricity because delocailsed electron

  Strong covalent bond as high melting boiling point

  Weak intermolecular forces as they can slide over each other

  Used for lubricants

  Strong covalent bonds as hexagon structure
• Diamond 


  Hard

  Insoluble high melting point

  4 c bond
• Properties of diamond 


  Does not conduct electricity no deicalised electron
• When analysing markets, a range of assumptions are made about the rationality of economic agents involved in the transactions
• The Wealth of Nations was written

  1776
• Rational


  (in classical economic theory) economic agents are able to consider the outcome of their choices and recognise the net benefits of each one
• Rational agents will select the choice which presents the highest benefits
• Producers act rationally by


  Selling goods/services in a way that maximises their profits
• Workers act rationally by


  Balancing welfare at work with consideration of both pay and benefits
• Governments act rationally by


  Placing the interests of the people they serve first in order to maximise their welfare
• Rationality in classical economic theory is a flawed assumption as people usually don't act rationally
• A firm increases advertising

  Demand curve shifts right
• Demand curve shifting right

  Increases the equilibrium price and quantity
• Marginal utility


  The additional utility (satisfaction) gained from the consumption of an additional product
• If you add up marginal utility for each unit you get total utility
• Doina


  Elements put into threes called Triads, with the middle element having the average mass of the other two
• Newland's law of octaves

  1. Arrange elements in order of atomic mass

  2. Every 8th element has similar properties
• Newland's law of octaves had inconsistent patterns further down the periodic table
• Mendeleev


  • Reordered some elements
  • Left gaps for undiscovered elements
• Modern periodic table


  • Arranges elements in order of atomic number
  • Includes noble gases
• Ionic bonding


  • Formed by transfer of electrons between a metal and a non-metal
  • Resulting ions are attracted by electrostatic forces
• Properties of ionic compounds

  • Exist as giant regular lattice structures
  • Have high melting and boiling points
  • Do not conduct electricity when solid (but can when molten or dissolved)
• Covalent bonding


  • Formed by sharing of electrons between non-metals
  • Resulting in a covalent bond
• Drawing dot-and-cross diagrams for covalent compounds

  1. Draw the central element

  2. Add the required number of bonding pairs and lone pairs
• Properties of covalent compounds

  • Have simple molecular structures
  • Have low melting and boiling points
  • Do not conduct electricity
• Allotropes


  Different structural forms of the same element
• Diamond


  • Each carbon has 4 covalent bonds
  • Has a giant tetrahedral structure
  • Has very strong covalent bonds, giving it a high melting point
• Graphite


  • Each carbon has 3 covalent bonds
  • Has layers of hexagonal rings that can slide
  • Has delocalized electrons, allowing it to conduct electricity
• Graphene


  • Single layer of graphite
  • Can be used to strengthen materials and in electronics
• Fullerenes


  • Small structures made of hundreds of carbon atoms
  • Can be used to transport drugs and as lubricants
• Carbon nanotubes


  • Can conduct heat and electricity
  • Have high tensile strength
• Metallic bonding


  Positive metal ions surrounded by a sea of delocalized electrons
• Metallic bonding occurs in pure metals