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• why do elements in the same group have similar properties?

  similar electron configurations (same number of outer shell electrons)
• what group of the periodic table are the alkali metals?

  why are they called the alkali metals?

  • group 1
  • they react with water to form alkaline solutions with a very high pH
• what are the general properties of the alkali metals?

  • low melting points
  • very reactive
  • soft
  • low density
• what gas is produced when an alkali metal reacts with water?

  hydrogen
• what are the products of the reaction between lithium and water?

  • lithium hydroxide
  • hydrogen
• what is the chemical equation for the reaction between sodium and water?

  2Na + 2H2O → 2NaOH + H2
• what is formed when an alkali metal reacts with oxygen?

  metal oxide
• what is the chemical equation for the reaction between lithium and oxygen?

  4Li + O2 → 2Li2O
• what is formed when alkali metals react with chlorine?

  metal chloride (white precipitates)
• why are alkali metals often stored in oil?

  to prevent them reacting with oxygen and water vapour in the air
• why are the alkali metals very reactive?

  they have one electron in their outer shell which they need to lose to obtain a stable electron configuration
• explain the trend of reactivity down group 1

  • reactivity increases down the group as the atomic radius and electron shielding increase so there is weaker attraction between the nucleus and the outer shell electron
  • this means the outer electron is lost more easily further down the group
• what is the name used to describe the elements in group 0 of the periodic table?

  noble gases
• what are the properties of the noble gases?

  • low boiling points
  • low density
  • inert
• what does chemically inert mean?

  very unreactive
• why are the noble gases chemically inert?

  they have full outer electron shells so are very stable
• describe the trend in boiling points down group 0

  boiling point increases
• what are the elements in group 7 of the periodic table called?

  halogens
• what is the colour and state of chlorine at room temperature?

  pale green gas
• what is the colour and state of bromine at room temperature?

  red-brown liquid
• what is the colour and state of iodine at room temperature?

  black solid
• why are the halogens at different states at room temperature?

  • because they have different melting and boiling points
  • as you go down group 7, melting and boiling point increases
• what are the properties of halogens?

  • increasing melting and boiling points
  • diatomic
  • reactive
• halogens are diatomic

  what does this mean?

  they form molecules containing two atoms, e.g. Cl2 , Br2
• what charge does a halide ion carry?

  why?

  • -1
  • e.g. Cl- , Br-
  • they gain one electron to obtain a full outer shell and a stable electron configuration
• what is the chemical equation for the reaction between bromine and sodium?

  Br2 + 2Na → 2NaBr
• describe the trend in reactivity of the halogens

  how does this affect the rate of reaction?

  • reactivity decreases down the group
  • rate of reaction also decreases down the group
• what is formed when hydrogen reacts with a halogen?

  hydrogen halide e.g. HCl, HBr
• chlorine reacts with hydrogen in the presence of sunlight but bromine requires a flame. why?

  reactivity decreases down the group so bromine requires more energy for the reaction to occur
• when does a halogen displacement reaction occur?

  when a more reactive halogen displaces a less reactive halogen from an aqueous solution of its halide ions
• why will halogen A only displace halogen B if A is above B in group 7?

  • reactivity decreases down the group.
  • the less reactive halogen is displaced by the more reactive halogen.
  • for displacement to occur, halogen A would have to be more reactive than B to displace it from the ionic compound so A has to be above B
• which halogens can chlorine displace?

  any halogens below chlorine in group 7
• which halogens cannot be displaced by bromine?

  chlorine and fluorine because they are above bromine in group 7 so are more reactive
• why can’t iodine displace chlorine or bromine from an aqueous ionic solution?

  • because iodine is below bromine and chlorine in group 7 and reactivity decreases down the group.
  • displacement will only occur if iodine is more reactive than the halogen in the ionic compound.
  • iodine could displace astatine
• write the word equation for the reaction between chlorine and potassium bromide

  chlorine + potassium bromide → potassium chloride + bromine
• write the word equation for the reaction between bromine and calcium chloride

  no reaction occurs because bromine can’t displace chlorine
• write the chemical equation for the reaction between bromine and potassium iodide

  Br2 + 2KI → I2 + 2KBr
• why does reactivity decrease down group 7?

  • halogens need to gain one electron to obtain a stable electron configuration.
  • as you go down group 7 atomic radius and electron shielding increase.
  • attraction between the nucleus and outer shell electrons decreases so it is harder for the atom to gain an electron meaning reactivity decreases.
• what colour are solutions of chlorine, bromine and iodine?

  • chlorine water - colourless
  • bromine water - orange
  • iodine solution - brown
• what would you observe when chlorine is added to potassium bromide?

  • Cl2 + 2KBr → Br2 + 2KCl
  • colour change from colourless (due to Cl2 ) to orange (due to Br2 )