Period 3 and their Oxides

• What are the properties of elements Na-Al?

  • Metal
  • Shiny
  • Electrical conductor
  • High melting and boiling points
• What are the properties of elements P-Ar

  • Non-metals
  • Electrical Insulators
  • Low melting and boiling points
• What are the properties of Si?

  • Metalloid
  • Semi-Conductor
  • High melting and boiling points
• What is the trend in atomic radius across period 3?

  Why?

  Decreases

  There are more protons yet the same number of shells meaning that electrons get pulled closer to the nucleus
• State and explain the trend in melting point across period 3

  • Increases from Na-Al due to stronger electrostatic attraction between positive cat-ions and delocalised electrons
  • Increases for Si as it is a macromolecule held together by strong covalent bonds
  • Decreases from P-Ar due to weak Van der Waals forces
• What is the general trend in first ionisation energies across Period 3?

  Increases
• What are the exceptions to trend in first ionisation energy and why?

  • Al due to the division in subshells
  • S due to additional repulsion within electrons in the p subshell
• What is the equation for the reaction of Sodium and water?

  $2Na\ (s)\ +$$\ 2H_2O\ (l)\ \rightarrow\ 2NaOH\ (aq)\ +$$H_2\ (g)$
• What is the reaction for Magnesium with WATER

  $Mg\ (s)\ +$$2H_2O\ (l)\ \rightarrow\ Mg\left(OH\right)_2\ (aq)\ +$$\ H_2\ (g)$
• What is the equation for the reaction of Mg with STEAM

  $Mg\ (s)\ +$$H_2O\ (g)\ \rightarrow\ MgO\ (s)\ +$$H_2\ (g)$