Structure and Bonding

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  • Created by: Kaitlin03
  • Created on: 13-09-19 11:35
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  • Structure and Bonding
    • States of Matter
      • They are described as by a simple model called the particle model.
        • The Particle model does have some limitations. it doesn't take into account the forces between the particles , the volume of the particles and the space between the molecules.
      • Changing States
        • particles stay the same. the way the particles are arranged changes. the way the particles move changes.
        • amount of energy required for a substance to change state depends on the amount of energy required to overcome the forces of attraction between the particles
    • Ionic Bonding
      • ions are formed when atoms gain or lose electrons, giving them an overall charge.
      • Involves a transfer of electrons from metal atoms to non-metal atoms.
      • The metal atoms lose electrons to become positively charged ions.
        • The non-metal atoms gain electrons to become negatively charged ions
      • The ionic bond is a strong electrostatic force of attraction between the positive metal ion and the negative non-metal ion.
      • Ionic Compounds
        • They are held together by electrostatic forces that act in all directions between oppositely charged ions.
        • Have high melting/boiling points
          • ionic bonds are very strong and it requires a lot of energy to overcome them.
        • Do not conduct electricity when solid (ions cant move)
        • do conduct electricity when molten or in a solution, because the charged ions are free to move to carry their charge.
        • Sodium Chloride.
    • Metals
      • Metallic Bonding
        • It occurs in metallic elements and alloys such as stainless steel.
        • Metals have a giant structure in which electrons in the outer shell are delocalised.
        • this produces a lattice of positive ions held together by electrostatic attraction to the delocalised electrons.
        • A metallic Bond is the attraction between the positive ions and the delocalised electrons
      • high melting/boiling points.
        • Good thermal and electrical conductors (delocalised electrons)
      • Alloys
        • mixtures with metal and at least one other element.
        • Pure metals are too soft for lots of uses
        • The added element disturbs the regular arrangement of metals so the layers don't slide past.
        • they are usually stronger and harder than pure metals.
    • Covalent Bonding
      • A shared pair of electrons between atoms which appear in non-metallic elements. Eg. Oxygen O2. And compounds of non-metals. .
      • They can be shown by using dot and cross diagrams.
      • Covalent bonds are very strong
      • Simple Molecules
        • Contain a small number of non-metal atoms joined together by covalent bonds.
        • no overall electrical charge so they cant conduct
        • Usually liquids and gases with low melting/boiling points.
          • Weak inter-molecular forces
            • Larger molecules mean stronger intermolecular forces- higher boiling/melting point
              • Going down group 7 the molecules get larger and their melting point increases.
                • Room temp: fluorine and Chlorine are gases.  Bromine is a liquid and iodine is a solid.
      • Giant Covalent Structures
        • Solids with very high boiling/melting points- strong covalent bonds.
        • Diamond is a form of carbon
          • four covalent bonds, very hard..
          • high melting/boiling point
          • NO charged particles- doesn't conduct
        • Graphite is another form of Carbon
          • High melting point
          • Forms 3 covalent bonds- layered hexagonal structure held together by weak inter-molecular forces
            • Layers slide past each other- graphite is soft and slippery.
            • Delocalised electron so it is a conductor
          • Graphene
            • A single layer of graphite, one atom thick.
            • strong, good thermal and electrical conductor and nearly transparent
            • useful in electronics and composite materials
        • Fullerenes
          • hexagonal rings of carbon. Sometimes contain five or seven carbon atoms
          • have hollow shapes, tubes, balls and cages
          • Buck minster fullerene C60- first to be discovered. Most stable
            • Carbon are cylindrical fullerenes with very high length to diameter ratios.
              • can be used to deliver drugs in the body, in lubricants, as catalysts for reinforcing materials.
    • Polymers
      • very large molecules and the atoms within the polymer molecules are held together by strong covalent bonds.
      • inter-molecular forces between the large polymer molecules are strong-solid at room temp
        • polyethene is produced when lots of ethane molecules are joinedtogether in addition polymerisation reaction.
          • Used to make plastic bottles and bags (cheap and strong)
    • Sizes of particles and their properties

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