Bonding and structure

• Definition of Ionic bond

  The electrostatic attraction between oppositley charged ions
• Common properties of Ionic substances

  -High melting/boiling point

  -Many are soluble in water

  -Don't conduct electricity as a solid (only as molten or aqueous)

  -They form giant lattice structures
• Factors affecting strength of Ionic bonds

  -Distance between oppositley charged ions

  -Size of Ions

  -Amount of charge on ions
• Why do ionic compounds have high melting/boiling points

  Due to the strong electrostatic attraction between cations and anions, which need large amounts of energy to overcome
• Why are Ionic compounds soluble in water

  Water is a polar solvent and forces can be pulled apart
• In what states do Ionic compounds conduct electricity

  Molten/aqueous
• What determines the size of ions/elements and why

  As you go down a group, an electron shell is gained therefore, sizes of ions increase as you go down a group
• Covalent bond

  The electrostatisc attraction between a shared pair of electrons and the bonded atoms
• What type of formula do we use to represent ionic compounds and why

  empirical formula because the exact number of atoms in the compound doesn't affect its properties
• What type of formula do we use to represent molecules

  Molecular formula because the exact amount of atoms does affect the properties of the molecule
• Properties of substances made of molecules

  They have low melting and boiling points

  They dont conduct electricity
• Dative covalent bond

  When one atom donates both electrons electrons in a shared pair of electrons
• Conditions to form a dative bond

  You need a molecule which has a lone pair of electrons to donate

  You need a molecule which doesn't have a full outer shell of electrons
• Metallic bond

  The electrostatic attraction beewteen cations and delocalised electrons
• physical properties of metals

  Hard

  Shiny

  malleable

  ductile
• Why are metals malleable and ductile?

  Layers of cations can slide over each other without breaking the metallic bonding
• Why do metals have high melting and boiling points

  There is a strong electrostatic attraction bewteen cations and delocalised electrons
• Why does boiling/melting point increase across a period

  Across a period, the ions in the lattice become more highly charged and the number of delocalised electrons per ion increases which means, there is greater electrostatic attraction
• Why does boiling/melting point decrease down a group

  Down a group, the size of the cation increases which means there is a larger distance beetween the cations nuclues and the delocalised electrons
• Alloy

  A metal that is made from two or more pure metals