3.2.1 - Periodicity

Cards (19)

  • What is periodicity? The repeating pattern of physical/chemical properties going across the periods
  • Atomic radius decreases from left to right across a period.
  • What does the block of an element tell you? The subshell in which the highest energy electron is in
  • How are elements in the periodic table arranged? Elements are arranged according to their proton number
  • What is a period on the periodic table? The horizontal rows
  • What is a group on the periodic table? The vertical columns.
  • What does the group number indicate on the periodic table? The number of outer electrons of an element.
  • What are the 4 blocks of the periodic table?
    • s block
    • p block
    • d block
    • f block
  • What elements are in each block of the periodic table?
    • s-block = groups 1 and 2
    • p-block = groups 3 to 0
    • d-block = transition metals
    • f-block = radioactive elements
  • Along a period, atomic radius decreases.
  • Going down a group, atomic radius increases.
  • Along a period, ionisation energy increases
  • Ionisation energy increases along a period

    Because:
    • atomic radius decreases, hence nuclear charge increases.
    • This means that the outer electrons are held more strongly so more energy is required to remove the outer electron and ionise the atom.
  • Going down a group, ionisation energy decreases
  • Ionisation energy decreases going down a group because:
    • The nuclear attraction between the nucleus and outer electrons reduces and shielding also increases.
    • Both of these factors mean less energy is required to remove the outer electron.
  • What does the melting point of Period 3 elements depend on?
    • The structure of the element
    • The bond strength
  • Melting points increase across Period 3 between sodium and aluminium because
    • Sodium, magnesium and aluminium are all metals with metallic bonding.
    • Their melting points increase due to greater positive charge of their ions
  • Why does the melting point increase dramatically for silicone in Period 3?
    • Silicon has a very strong covalent structure.
    • So more energy is required to break the strong covalent bonds - giving it a very high melting point
  • Why does argon have an even lower melting point than chlorine ?
    • Argon is a noble gas that exists as individual atoms with a full outer shell of electrons.
    • This makes the atom very stable and the van der waals forces between them very weak.