ATOMIC STRUCTURE

• number of electrons =

  number of protons
• mass of proton


  1
• mass of neutron


  1
• mass of electron


  less than 1
• draw helium 


  helium

  
• properties of metals

  • HBP - strong bond
  • hard
  • malleable - in a layer of atoms so atoms can slide easily
  • conductor of heat and electricity - sea of electrons
  • shiny
  • group 1 and 2, transition metals
  • ductile
  • metallic bonding - metals + metal
• electrostatic attraction of positive metal ions

  due to the sea of electrons --> delocalised electrons --> so positive charge

  
• what is the arrangement in metals

  regular arrangement (giant lattice) - structure
• alloy


  2/more elements, at least one is metal
• ionic bonding


  • gaining/losing electrons to obtain full outer shell to become stable ---> changes reactivity of atom
  • group 0 (less reactive) atoms do not need to bond
  • atoms with electrons don't form ions, stay neutral
  • metals+non-metals
• ionic bonding between sodium and chloride:

  Na + cl ---> NaCl

  
• ion


  • charged atom, by gain/losing an electron
  • has a lattice structure
  • conduct electricity when molten/dissolved --> lattice is broken so ions move easily --> when dissolved, can also carry electric current
  • opposite charges attracted to each other due to very strong electrostatic forces --> act in all directions --> very strong bond -->HMP+HBP --> takes a lot of energy to break up lattice --> lot of heat needed
• oxidation


  loss of electron, so positive
• reduction


  gain of electron, so negative
• covalent bonding


  • non-metal + non-metal
  • atoms share electrons --. pairs (max. 3)
  • very strong bond
  • no charge --> no free electrons --> cannot conduct electricity
  • giant lattice
• covalent bonding between fluorine and fluorine

  F2

  
• simple covalent molecule


  • molecule - 2/more atoms chemically joined together
  • simple - 2/3 atoms
  • don't conduct electricity
  • weak intermolecular forces --> especially in gas form

  
• allotrope


  diff form of the same element
• allotropes of carbon


  diamond and graphite
• diamond


  • all electrons (on outer shell) of carbon atom involved in forming covalent bonds
  • very hard ---> giant covalent structure --> strong
  • HBP, HMP -->lots of energy
  • cannot conduct electricity --> no free electrons to carry charge
  • each carbon atom is bonded to 4 others

  
• isotopes

  atoms with same atomic number, but different number of neutrons
• graphite


  • only three of 4 electrons in outer shell of carbon atom involved in covalent bonds
  • individual layers called graphene --> weak forces of attraction --> easily broken + layers can slide over each other --> graphite is soft and slippery
  • conducts electricity - free electrons, delocalised --> can carry charge

  
• buckminsterfullerene


  • hollow sphere
  • 60 carbon atoms (simple structure) --> can't form lattice
  • can conduct electricity ---> delocalised electrons
  • used in medicine
  • high tensile strength
  • large surface area
• nanotubes

  • made from carbon atoms
  • have excellent thermal heating
  • can conduct electricity