Periodicity

• What is periodicity?

  Is a repeating pattern in either physical or chemical properties, across different periods
• How does the electron arrangement in Chromium differ from other elements?

  .

  • Chromium fills the d orbital in the third energy level with 5 electrons, this is achieved by using one of the electrons from the s orbital in the fourth energy level.

  
• How does the electron arrangement in Copper differ from other elements?

  .

  • Copper fills the d orbital in the third energy level with 10 electrons, this is achieved by using one of the electrons from the s orbital in the fourth energy level.

  
• Describe the ionisation energies in this graph for aluminium.

  .

  • There is a jump after the third ionisation energy, this signifies a change in energy levels. Therefore this shows that aluminium is in group 3
  • There are two significant jumps in ionisation energy, suggesting that there are three energy levels. Therefore this shows aluminium is in period 3.

  
• What is the first ionisation energy?

  The energy required to remove one mole of electrons from each atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions.
• How are elements arranged on the periodic table?

  They are arranged in order of increasing atomic number
• What are the horizontal rows on the periodic table known as?

  Periods
• What are the vertical columns on the periodic table known as?

  Groups
• What are the trends between elements in the same group as each other?

  .

  • Melting point
  • Boiling point
  • Atomic radius
• What does the addition of an extra outer shell lead to?

  .

  • Increased atomic radius
  • Greater electron shielding

  Therefore greater ionisation energy is required
• How do you measure the atomic radius?

  It is impossible to measure the distance from the nucleus to the outermost electron of an atom.
• What does the Heisenberg's uncertainty principle state?

  That we are unable to locate where the outermost electron is exactly.
• What is the bonding structure across a period?

  Na Mg Al- giant metallic lattice

  Si P S Cl- simple molecular covalent Ar- simple atomic
• What is the bonding structure across a group?

  C- non-metallic giant covalent lattice

  Si Ge- show properties associated with non-metals and can be regarded as being metalloid

  Sn Pb- metallic, giant metallic lattice