Chp11 periodic table

• Group number


  Number of valence electrons
• Period number


  Number of electron shells
• Elements arranged in order of

  Increasing proton (atomic) number
• Same group


  Similar chemical properties
• Going down a group


  Metallic properties increase whilst nonmetallic properties decrease
• Metalloids


  Elements that have properties of both metals and nonmetals
• Valence electrons increase


  Metallic properties decrease
• Fewer valence electrons


  Lose electrons - metallic
• More valence electrons


  Gain electrons - nonmetallic
• Alkali metals (group 1) have pH more than 7
• Physical properties of alkali metals

  • Soft, can be cut easily
  • Shiny silvery surface that tarnishes once exposed to air
  • Have low melting and boiling points
  • Have low densities, Li, Na and K float on water
• Going down the group of alkali metals


  Melting points decrease & densities generally increase
• Going down a group

  Size of atom increases
• Going down a group

  Distance between valence electrons and nucleus increases
• Going down a group

  Attraction between valence electrons and nucleus weakens
• Going down a group


  Reactivity of group 1 elements increases
• Chemical properties of group 1 metals when reacting with water

  • Lithium-reacts quickly. Floats on water.
  • Sodium-reacts violently. Darts around water surface.
  • Potassium-reacts very violently. Explosive.
• Alkali metals stored in oil to keep them from reacting with oxygen or moisture in the air as they are extremely reactive
• Going down the group of alkali metals


  Reactivity increases
• Order of reactivity of alkali metals


  • Lithium
  • Sodium
  • Potassium
  • Rubidium
  • Caesium
  • Francium
• Halogens (Group 17) exist as diatomic molecules ONLY
• Physical properties of halogens

  • Low melting and boiling points
  • Coloured
• Going down the group of halogens

  • Melting and boiling points increase
  • Colour intensities increase
• Going down the group of halogens

  Reactivity decreases
• Noble gases (group 18)

  • Have full valence shells hence are inert (unreactive) gases
  • Monoatomic nonmetals
  • Colourless gases at room temperature
  • Have low melting and boiling points
  • Insoluble in water
• Noble gases do not lose, gain or share electrons. They are chemically unreactive