Periodicity’

• Periodic table

  Elements are arranged in the order of increasing atomic numbers
• Period

  The horizontal rows in the periodic table
• Group

  The vertical columns in the periodic table
• Periodicity

  The repeating trends in chemical and physical properties
• Elements change from metals to non-metals across each period
• Electron configuration shorthand

  The noble gas before the element is used to abbreviate, e.g. Li → [He] 2s1
• First ionisation energy

  The energy required to remove one electron from each atom in one mole of the gaseous element to form one mole of gaseous 1+ ions
• First ionisation energy of magnesium

  Mg (g) → Mg+ (g) + e-
• Factors affecting ionisation energy

  • Atomic radius
  • Nuclear charge
  • Electron shielding or screening

  
• Across period 3

  First ionisation energy increases due to increased nuclear charge, decreased atomic radius, and same electron shielding

  
• Between group 2 and 3

  First ionisation energy decreases because in group 3 the outermost electrons are in p orbitals whereas in group 2 they are in s orbitals, so the electrons are easier to remove
• Between group 5 and 6

  First ionisation energy decreases because in group 5 the outermost electrons are single in p orbitals, whereas in group 6 they are spin paired, with some repulsion, making them slightly easier to remove
• Between the end of one period and the start of the next

  First ionisation energy decreases due to increase in atomic radius and electron shielding

  
• Down a group

  First ionisation energy decreases due to increased shielding and atomic radius, which outweighs the increase in nuclear charge
• Properties of giant metallic lattices

  • High melting and boiling point
  • Good electrical conductors
  • Malleability
  • Ductility
• Ductile metal

  The metal can be stretched and made into wires
• Malleable metal

  The metal can be shaped into different forms
• Structure, forces and bonding in period 2 elements

  1. Li & Be → giant metallic, metallic bonding

  2. B & C → giant covalent, covalent bonding

  3. N2, O2, F2, Ne → simple molecular, covalent bonding within molecules and intermolecular forces between molecules
• Structure, forces and bonding in period 3 elements

  1. Na, Mg, Al → giant metallic, metallic bonding

  2. Si → giant covalent, covalent bonding

  3. P4, S8, Cl2, Ar → simple molecular, covalent bonding within molecules and intermolecular forces between molecules