Bonding

• Ions: atoms that have gained or lost electrons to gain a charge (valency)
• Ionic Bonding: between metal and non-metal atoms (electrons are transferred from the metal to non-metal)

  Metal = lose electron

  Non-metal = gain electron
• Naming Ionic compounds

  _metal_ _non-metal_. (change non-metal end to "-ide" for monatomic ions - one type of atom)

  Chlorine = chloride

  Fluorine = fluoride

  Bromine = bromide

  Oxygen = oxide

  Nitrogen = nitride

  Phosphorus = phosphide
• Structure of ionic compounds - always opposite forces

  -neg-pos-neg-pos-

  -pos-neg-pos-neg-

  -neg-pos-neg-pos-
• Covalent bonds form because atoms share electrons to create a full outer shell in order to become stable - this means that there are no positive or negative charges as the electrons are shared.
• Covalent bonds - only between non-metals
• Structure of covalent molecules.

  A) Intermolecular force = ------

  B) Covalent bonds

  
• Covalent molecules have a low boiling and melting point as the intermolecular force is weak, and doesn't need a lot of energy to break (energy = heat) therefore causing the low melting + boiling point.
• Electron dot diagrams/Lewis diagram - shows how the valence electrons are shared between atoms.

  
• Covalent naming and formula - prefix tells us how many atoms we have (mono, di, tri, tetra, pent, hex, oct, non, dec)

  E.g. CO2 - carbon dioxide

  E.g. PCl3 - phosphorus trichloride

  E.g. HCl - hydrogen chloride (EXCEPTION TO MONO)
• The structure of ionic compounds in solids: called 3D lattices of alternating positive and negative ions which are held together by electrostatic attraction (positive attracts negative).
• The electrostatic attraction is the ionic bond and is very strong.
• Ionic compounds have high melting and boiling points as the ionic bond is very strong and takes a lot of energy to break.
• Ionic compounds are hard because the atoms are tightly packed (very dense) and the strong ionic bond.
• The structure of an ionic solid.

  
• Metallic bonding is metal atoms only. Same element = pure metal. Mixture of metals = alloys (e.g. stainless steel).
• The metallic structure of a solid: a lattice of positive metal ions surrounded by a sea of delocalised (free to move) electrons.

  • Despite the ions only being positive so they should repel, they are held together by the localised electrons (the valence electrons that have been emitted) which have a negative charge.
• The metallic bond in metallic compounds is very strong.
• Metallic compounds are malleable - means they can be hammered into different shapes without breaking apart (because the electrons are delocalised and can flow freely without breaking).
• Metallic compounds have a high melting and boiling point as the metallic bonds are strong so it takes a lot of energy to break.
• Metallic compounds are hard because they are tightly packed and the metallic bond is strong.
• Metallic compounds are ductile - means you can pull them into thin wires (because the electrons are delocalised and can flow freely without breaking).