Bonding

• Ionic bonding:


  1 atom loses an electron to form a cation & another atom gains this electron to form an anion.

  Positive & negative ions held together by attraction between positive & negative charges.

  (metal + non-metal)
• What do anion names often end in?


  ide

  e.g, chloride
• What is a giant ionic lattice?


  3D array of ions formed
• What is a unit cell?


  Simple repeat unit in structure
• Covalent bonding:


  2 atoms share a pair of electrons
• Define a covalent bond:


  A pair of electrons placed between 2 atoms that acts as an attractive force on nuclei of both atoms
• What is a perfectly (100%) covalent bond?


  Both atoms have identical electronegativity

  (electron pair exactly halfway between the 2 atoms)
• How are polar covalent bonds made?

  Elements with different electronegativities

  (electronegativity difference not big enough for ionic bonding to take place)

  Dipole created as electron pair unevenly shared (strengthens bond)
• Why is there no such thing as a 100% ionic bond?


  Small amount of electron sharing occurs
• What is a hydrogen bond?


  A hydrogen atom acts as a bridge between 2 electronegative atoms