3.1.1 - periodicity

• Some Typical General Properties of Metals

  • Solid at room temperature except Mercury
  • Shiny surface (metallic lustre, lustrous = shiny)
  • Malleable - can be beaten into shape
  • Ductile - can be drawn into wires
• Some Typical General Properties of Metals

  • Good conductors of heat and electricity
  • Form positive ions by electron loss
• Some Typical General Properties of Non-Metals

  • Can be solids, liquids or gases at room temperature
  • Do not usually have a shiny surface
  • Not Malleable - cannot be beaten into shape (too brittle)
  • Not Ductile - cannot be drawn into wires
• Some Typical General Properties of Non-Metals


  • Poor conductors of heat and electricity
  • Form negative ions by electron gain
  • Form many compounds by covalent bonding
• Lavoisier sorted 33 elements into his periodic table
• Döbereiner looked at the recently discovered Bromine and saw it had properties half way between chlorine and iodine
• Law of Octaves

  The known elements were arranged in horizontal rows, seven elements long, by increasing atomic mass
• Mendeleev's periodic table


  • Mendeleev listed the known elements in rows or columns in order of atomic mass
  • Mendeleev started a new row or column when if an element's characteristics was repeated
  • Mendeleev left gaps in his the table, if he thought an element had not been discovered
• Mendeleev's table succeeded, as he left gaps in his the table, if he thought an element had not been discovered
• The energy needed to form positive ions is known as the ionisation energy

  
• First ionisation energy (1st I.E.)

  A measure of how easily an atom looses an electron to form a 1+ ion

  
• Factors affecting ionisation energy

  • Atomic radius - the further the outer electrons are from the nucleus, the less attraction they experience
  • Nuclear charge - the more protons, the greater the nuclear charge, the greater the attraction felt by the outer electrons
  • Electron shielding - inner shells of electrons repel the outer ones, the more inner shells there are the larger the effect and the lower the attraction felt by the outer electrons

  
• As each electron is removed, there is less repulsion between the electrons and each shell will be drawn slightly closer to the nucleus

  
• There is a general increase in first ionisation energy across a period

  
• 1st IE's decrease down a group
• There is a general increase in boiling point across each period from group 1 to 4