structure and bonding

• metal atoms bond to eachother through metallic bonding, forming a lattice with delocalised electrons
• what are delocalised electrons?

  electrons that are not exactly on the atom and are free to move
• what makes metals so good?

  good conductors of electricity and heat
• how do metals bond to non-metals?

  through ionic bonding
• in ionic bonding the charges of all ions in a compound must add up to 0
• chemical formula for Barium Oxide?


  Be2+ and O2-
• chemical formula for Barium Chloride?

  Be2+ and 2Cl-
• what are ionic bonds?

  Bonds formed between ions through electrostatic attraction in a lattice structure.
• structure of ionic compounds?

  • giant ionic lattice - 3-dimensional structures
  • they do not conduct electricity when a solid only when molten or dissolved
  • have high boiling points
  • soluble
• 3 ways to represent ionic compounds

  • dot and cross diagram
  • 3D models
  • ball and stick models
• ionic bonds have high boiling points= strong electrostatic forces of attraction between ions require lots of energy to overcome
• 1 + about dot and cross diagram?

  shows what the ionic compound is formed from
• 2 - dot and cross diagram?

  • doesnt always show sizes of ions/structures
  • doesn't show how ions are arranged
• 2+ 3d models

  • shows relative sizes of ions
  • shows regular patterns of ionic compounds
• 1 - 3D models

  • only shows outer layer of compound
• 3 + Ball and stick diagram

  • shows regular pattern of ionic compound
  • suggests compound extends beyond the diagram
  • sometimes shows sizes of ions
• 2- ball and stick diagram

  • sometimes doesnt show sizes of ions
  • suggests there are gaps between the ions when there isn't
• what are ionic compounds?

  giant structure of ions held together in a lattice by strong electrostatic forces between oppositely charged ions= ionic bonds
• what are ionic bonds?


  strong electrostatic forces of attraction that hold positively charged ions together in an ionic compound
• how are ionic compounds held together?

   strong electrostatic forces of attraction between oppositely charged ions
• when might ionic bonds be formed?

  when a metal and a non-metal reacts, the metal loses electrons and the non-metal gains them. they form a + and - ions and become ionically bonded
• what type of ions do metals form and how?

  metal ions lose electrons and form + ions
• what type of ions do non-metals form and how?

  non-metal ions gain electrons and form - ions
• any ionic compound can be called a salt
• non-metals bond through covalent bonding to form molecules by sharing electrons
• explain why small covalent molecules have a low melting and boiling points?

  atoms are held by strong covalent bonds

  very weak intermolecular forces
• how are intermolecular forces broken?

  as temp increases the molecules vibrate more and break the intermolecular forces holding the molecules to eachother= turns into gas
• weak intermolecular forces dont require lots of energy
• what is intermolecular forces?

  Forces between molecules
• the bigger the covalent molecules the intermolecular forces increas
• chlorine gas is C12 formed by each chlorine atom sharing an electron with another
• Nitrogen (N2) has a triple bond in covalent bonding
• in covalent bonding the number of electrons an atoms needs is the same as the number of bonds it makes
• what structure are covalent bonds not being broken into?

  simple molecular
• simple molecular structures have a low BP due to weak intermolecular forces so molecules can mix together
• unlike ionic compounds, simple covalent structures cannot conduct electricity even as liquids
• what are giant covalent bondings?

  atoms form covalent bonds to other atoms forming a giant molecule
• 4 giant covalent structures?

  • diamond
  • graphite
  • graphene
  • fullerenes
• what are diamonds?


  crystals of carbon atoms bonded together very hard with high MP
• what is graphite?


  layers of carbon atoms with delocalised electrons between layers- can conduct electricity and slide over eachother