C6

• How are elements arranged in the periodic table?

  Ordered by increasing atomic number

  Elements in the same group (column) have the same number of outer shell electrons

  Elements in the same period (row) have the same number of electron shells
• Why do elements in the same group have similar chemical properties?

  They have the same number of electrons in the outer shell
• What group of the periodic table are the alkali metals?

  Group 1
• List 2 properties of alkali metals

  • Relatively low melting points
  • Soft
• Why are group 1 elements called the alkali metals?

  They react with water to form alkaline solutions (pH greater than 7)
• What are the products of the reaction between lithium and water?

  Lithium hydroxide and hydrogen
• Why should alkali metals be stored in oil?

  To prevent them reacting with water vapour and oxygen in air
• What would be observed when lithium reacts with water?

  • Slowest reaction of alkali metals
  • Bubbles of hydrogen produced
  • Doesn't melt (highest melting point)
• What would be observed when sodium reacts with water?

  • Faster reaction than lithium
  • Floats on surface of water (less dense)
  • Bubbles of hydrogen produced that cause the sodium to whizz around surface of the water
  • melts as enough energy is given out to meet sodium's melting point
• What would be observed when potassium reacts with water?

  • More violent reaction than sodium
  • Bubbles of hydrogen produced which cause the potassium to whizz around the surface of the water
  • Melts into a shiny ball
  • Burns with lilac flame
• Using the reactions of the first 3 alkali metals with water, predict the reactivity trend down group 1

  Reactivity increases down group 1
• Why does reactivity increase down group 1?

  The number of electron shells increases down the group so there is more electron shielding. As a result there is weaker attraction between the positive nucleus and outer shell electron. This means it is easier to remove an outer shell electrons to form a positive metal ion
• Which group 1 element would you expect to react most violently with water?

  Reactivity increases down the group so francium will react most violently with water
• What group are the halogens in?

  Group 7 because they have 7 outer shell electrons
• What is the colour and state of chlorine at room temp?

  Pale green gas
• What is the colour and state of bromine at room temp?

  Red-brown liquid
• What is the colour and state of iodine at room temp?

  Black solid
• Why are the halogens at different states at room temp? What is the trend down the group?

  At room temp, chlorine is gaseous, bromine is liquid and iodine is solid because they have different melting and boiling points. As you go down the group, melting and boiling point increases
• What state would you expect the halogens fluorine and astatine to be at room temp?

  Fluorine is above chlorine so should have a boiling point lower than chlorine. This means it would be a gas at room temp.

  Astatine is below iodine in group 7 so should have a higher melting point. Therefore you can predict it would be a solid at room temp
• Why does melting and boiling point increase down group 7?

  The molecules get bigger down the group so there are more intermolecular forces to overcome during melting / boiling so more energy is required
• What is the chemical test for chlorine?

  Damp litmus paper placed into a test tube of gas. If chlorine is present, the litmus paper will turn red then white due to the bleaching effect of chlorine
• Halogens are diatomic. What does this mean?

  They form molecules consisting of 2 atoms
• What charge does a halide ion carry?

  -1

  They gain one electron to have a stable electron configuration
• What is produced when a halogen reacts with a metal?

  Metal halide salt
• Predict the product of the reaction between magnesium and fluorine

  Magnesium fluoride
• Write a word equation for the reaction between iodine and potassium

  Iodine + Potassium -> Potassium iodide
• Describe the trend in reactivity of the halogens. How does this affect the rate of reaction?

  Reactivity decreases down group 7.

  Rate of reaction decreases down group 7
• What is formed when hydrogen reacts with a halogen?

  Hydrogen halides
• 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
• What is formed when a hydrogen halide dissolves in water?

  An acidic solution. Hydrogen ions dissociate, making the solution acidic
• Predict the product of the reaction between hydrogen and fluorine

  Hydrogen fluoride
• When does a halogen displacement reaction occur?

  When a more reactive halogen displaces a less reactive halogen from an aqueous solution of its halide
• Why will halide ions A only be displaced by halogen B is B is above A in group 7?

  The most reactive halogen (B) will displace the less reactive halogen (A) to become part of the ionic compound. reactivity increases as you go up the group so B must be higher in group 7 to be more reactive than A
• Which halogens can chlorine displace from an aqueous ionic solution?

  Chlorine can displace any halogens below it in group 7. It will displace iodine and bromine
• Which halogens cant be displaced from an aqueous ionic solution by bromine?

  Bromine cant displace any halogens above it in group 7. These are chlorine and fluorine
• Why can iodine not displace chlorine or bromine from an aqueous ionic solution?

  Because reactivity decreases down the group and iodine is below chlorine and bromine in group 7. Displacement will only occur if iodine is more reactive than the halogen in the ionic compound
• Write the word equation for the reaction between chlorine and potassium bromide

  Chlorine + potassium bromide -> potassium chloride + bromine
• Which halogens would you expect astatine to be able to displace?

  None of them. It is at the bottom of group 7 so has the lowest reactivity
• Why does reactivity decrease down group 7?

  As you go down group 7, the outer shell is further from the nucleus and electron shielding increases. Attraction between the nucleus and outer electrons decreases so it is harder for the atom to gain an electron meaning reactivity decreases
• What colours are solutions of chlorine, bromine and iodine?


  Chlorine water - colourless

  Bromine water - orange

  Iodine solution - brown