ions

• Why do ionic compounds have high melting and boiling points?

  • oppositely charged ions held together by strong electromagnetic forces of attraction
  • this holds the ions in a giant ionic lattice shape
  • these bonds require lots of energy to break
  • need to get the energy from heat hence why they need more heat to break these bonds.
• Electron:


  A negatively charged particle in an atom, found in the shells (also called electron levels) around the outside of the nucleus.

  In an atom, there are the same number of electrons as protons
• Ion:


  A changed atom. It has lost or gained electrons
• Compound:


  Two or more elements chemically bonded together
• Cation: 


  An ion with a positive charge
• Anion:


  An ion with a negative charge
• Oxidation:


  when something gains oxygen or loses electrons in a reaction
• Reduction:


  When something loses oxygen or gains electron during a reaction
• Ionic compounds and conduction:

  Ionic compounds cannot conduct as solids. This is because the ions aren't free to move- they are held together by strong electrostatic forces of attraction in a giant ionic lattice.

  Ionic compounds can conduct when molten or in a liquid. This is because the ions are free to move from the structure and carry charge from one location to another.
• Crossover method:

  This method is used to find the formula of an ionic compound. First you calculate the charges on the ions involved. You use their group number to find this. Then you lose the positive and negative signs, swap the charges between the metal and non-metal and drop the number to be at the bottom, behind the element. Finally you would simplify the ratio (e.g. for Mg2O2 we would just write MgO). Remembering to put brackets around any complex ions.
• Ionic bonding between magnesium and iodine:

  Magnesium has two electrons in its outer shell. To become an ion it can lose two electrons and have a charge of +2. Iodine has seven electrons in its outer shell so it has toga one electron to have a charge of -1. Magnesium reacts with two iodine atoms to donate one electron to each atom. An electrostatic force of attraction forms between the positive and negative ions. This is called an ionic bond.
• Solids


  • Regular arrangement of particles
  • Particles fixed in position
  • Particles have little energy, can only vibrate on the spot
  • Particles held together by strong electrostatic forces of attraction
• Liquids


  • Particles randomly arranged
  • Strong electrostatic forces must be overcome when solid melts to become liquid
• Ionic compounds


  Have high melting points
• Why ionic compounds have high melting points

  1. Ions held together in a giant ionic lattice

  2. Strong electrostatic forces of attraction between oppositely charged ions

  3. Require a lot of energy to be broken
• Reducing agent:


  Gives electrons to something that is reduced, is itself oxidised and gains electrons.
• Oxidising agent:


  Takes electrons from something that is oxidised, is itself is reduced