C2

• History of the periodic table:

  • John Newlands and Dalton were the first to make a periodic table; they ordered elements by atomic mass however some were still in inappropriate groups
• History of the periodic table:

  • Dmitri Mendeleev, arranging by atomic mass, added gaps to Newlands’ table, predicting undiscovered elements, even predicting their properties and masses e.g. Aluminium
  • The modern periodic table is the same as Mendeleev’s, except the gaps are filled and elements are arranged by atomic number
• Properties of metals:

  • lustrous (shiny)
  • good conductor of heat and electricity
  • high density
  • sonorous
  • solid (except mercury)
  • malleable
• Properties of non-metals:

  • dull
  • poor conductor of heat and electricity
  • weak
  • brittle
  • low density
  • solid, liquid or gas
• Alkali metals

  • group 1
  • highly reactive because only 1 electron in outer shells that is usually lost in reactions
  • reactivity increases going down the group, as there are more energy shells and there is less attraction between the outer shell and nucleus
  • stored in oil so they don’t oxidise
  • density decreases going down the group
  • melting and boiling points decrease going down
  • unique: soft and low density
• Alkali metals when reacting with water:

  • metal floats on the surface and melts to form a metal hydroxide e.g. lithium hydroxide
  • when they react, the energy released is enough to melt them
  • the universal indicator turns blue because alkaline
• Alkali metals when reacting with chlorine:

  • a metal chloride is formed which then dissolves in water to give a colourless solution e.g. potassium chloride
  • produces a salt e.g. potassium chloride
• Alkali metals when reacting with oxygen:

  • rapidly changes from shiny to dull as a metal oxide is produced e.g. potassium oxide
• Group 1 includes:

  • lithium (Li)

  *electron structure of 2, 1

  *least reactive of the group

  *burns a crimson flame when reacted with oxygen

  *floats on the surface of the water and fizzes, producing hydrogen gas
• Group 1 includes: sodium (Na)

  *electron structure of 2, 8, 1

  *more reactive than lithium because the outer electron is further away from the nucleus

  *floats on water, which releases enough heat to melt it

  *burns with yellow flame
• Group 1 includes:

  • potassium (K)

  *electron structure 2, 8, 8, 1

  *more reactive than lithium and sodium because the outer shell is even further away from the positive nucleus

  *floats on water and has a similar reaction to sodium

  *burns with a lilac flame when reacting with oxygen
• Transition metals

  • middle of the periodic table
  • good conductors of heat and electricity
  • malleable and ductile (not brittle)
  • relative to alkali metals
  • higher melting points - used in cooking materials
  • higher density - used in construction
  • greater strength and hardness
  • lower reactivity than alkali metals - e.g. iron takes weeks to rust with oxygen and water, whereas sodium takes a few seconds
• Transition metals: special properties

  • have different ion charges
  • can form different colour compounds - e.g. copper (l) sulphate is white and copper (ll) sulphate is blue
  • can act as catalysts - e.g. iron catalyses the Haber reaction, where ammonia is produced
  • can form alloys: a metal made by combining two or more metallic elements, to give greater strength or resistance to corrosion - e.g. an alloy of nickel, bronze, and zinc
• Halogens

  • group 7
  • 7 electrons in the outer shell
  • when they react, they gain 1 electron, forming a negative ion
  • react with metals to form ionic compounds
  • diatomic molecules
  • when a metal atom transfers its outer electron to a halogen, a salt is formed
  • moving down the group, the reactivity decreases because:

  *atom gains more electron shells

  *distance between the outer shell and nucleus increases

  *attraction between the nucleus and electron to be gained decreases
• Noble gases

  • Group 0 (8)
  • similar properties, one of which is colourlessness
  • unreactive because of full outer shells
  • can be used in light bulbs as won’t react with a hot metal filament
  • monatomic because of unreactivity
  • low boiling points, but they do increase going down the group because relative atomic mass increases
  • low densities, but do increase going down the group e.g. are good for balloons
  • do not form molecules