Chapter 11: Periodic Table

• Group 1 elements are alkali metals
• Group 17 elements are halogens
• Group 18 elements are noble gas
• From left to right, oxides go from basic to acidic
• generally,

  • metals form basic oxides
  • non-metals form acidic oxides
  • metalloids form amphoteric oxides
• Metallic properties down a group

  • increase in metallic properties
  • decrease in non-metallic properties
  • size of atoms increase = outermost electrons furthest away from nucleus -> electrostatic forces of attraction between outermost shell and protons in the nucleus becomes weaker -> outermost electron is lost more easily. Therefore, atoms become more metallic down group
• Physical properties of Alkali Metals

  • most reactive elements in Periodic Table
  • shiny solids
  • very soft, can be cut easily with a knife
  • tarnish quickly (very reactive)
  • shiny metallic surface corrode rapidly in air and so are kept under oil
  • low melting and boiling point
  • low density
  • good conductors of electricity
• Lithium (Li) + Water

  • reacts quickly
  • floats on water
• Sodium (Na) + Water

  • reacts violently, sodium darts around water surface
  • reaction may be explosive
• Potassium (K) + Water

  • very violently
  • reaction is explosive
• Rubidium (Rb)

  • reacts very explosively
• Properties of Halogens

  • very reactive non-metals
  • able to gain an electron to form halide ions (1- charge)
  • exist as diatomic molecules
  • low melting and boiling points
  • non-conductors of electricity
  • coloured
• flourine (f2) is pale yellow
• chlorine (cl2) is yellow-green
• bromine (br2) is reddish-brown
• iodine (i2) is purple-black
• astatine (at2) is black
• Chemical properties of Halogens

  • react with most metals to form compounds called metal halides
  • can undergo displacement reactions with metal halide solution
  • order of reactivity decreases down the group
• Displacement reaction is a reaction in which one element takes place of another element in the compound
• A more reactive halogen will displace a less reactive halogen from its metal halide solution
• Properties of Noble Gases

  • low melting and boiling point
  • inert due to stable electronic configuration
  • colourless gas that are insoluble in water
• Applications of noble gases

  • helium - filling weather and advertisement balloons
  • neon - making coloured lamps, used as advertising lights
  • argon - used to fill up electric light bulbs