Chemistry Revision on Structure & Bonding

Chemistry Revision on Structure & Bonding

1. Bonding

   • Ionic
     • metals lose electrons and become positive
     • non-metals gain electrons and become negative
     • has high melting and boiling points
     • does not conduct electricity when solid
   • Covalent
     • non-metals only
     • electrons are shared
     • Covalent Compounds
       • have no free electrons
       • do not conduct electricity
       • usually gases or liquids at room temp.
     • bonds between atoms are strong
     • intermolecular forces are weak

2. Alloys

   • mixture of metals
   • different sized atoms
   • layers are distorted
   • difficult for layers to slide over each other
   • harder than the pure metal

3. Polymers

   • Thermosoftening
     • intermolecular forces are weak
     • melt at low temps.
     • little energy needed to break forces
     • not suitable for packaging hot food
   • Catalyst
     • speeds up reaction
     • does not get used up

4. Graphite and Diamond

   • Graphite
     • each carbon atom is covalently bonded to three others
     • has free electrons
       • conducts electricity
     • layers are able to slide over each other
     • weak intermolecular between layers
   • Diamond
     • each carbon atom is covalently bonded to four others
     • has no free electrons
       • does not conduct electricity
     • no atoms are able to move/slide

5. Nanoparticles

   • between 1 and 100 nm in size
   • have large surface areas than normal sized particles

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