C2 | Mindmap

atoms
1. Nucleus
  1. neutron
    1. no charge
    2. same mass as proton
  2. proton
    1. number of protons equals the number of electrons
    2. positively charged
  3. positively charged because of the protons in the nucleus
2. electron (around the nucleus)
  1. negatively charged
  2. has no mass
  3. occupy shells around the nucleus
3. electron and proton charge cancel each other out
4. becomes an ion when electrons are lost or gained making the ion charged (number of protons no longer equals the number of electrons)
5. mass number= number of protons+number of neutrons
6. atomic number= number of protons
7. Isotopes are different atomic forms of the same element which have the same number of protons but a different number of neutrons
Bonding
1. ionic
  1. atoms gain or lose electrons
  2. form charged ions
  3. group one and two atoms do ionic bonding most because they only have one or two electrons in their outer shell so are keen to lose them (form +ve ions - cations)
  4. group six and seven atoms are equally as keen to bond ionically as group one and two as they only need one or two electrons (gain elecctrons, form -ve ions - anions
  5. the ions from then react with each other as they will be oppositely charged and oppositely charged ions attract - the cations and the anions react to form ionic bonds
  6. ionic bonds produce giant ionic structures
    1. closely packed regular lattice
    2. very strong chemical bonds between all the ions
      1. high melting and boiling points
    3. When they are dissolved (or melted), the ions separate, the electrons are then free to move so can carry a current
  7. only elements at opposite sides of the periodic table can form ionic bonds - group 1+7, group 2+6
2. covalent
  1. atoms share electrons with other atoms
  2. some covalent bonds form giant covalent structures
    1. similar to giant ionic but no charged ions
    2. all atoms are bonded together with strong covalent bonds
    3. very high melting and boiling points
    4. they don't conduct electricity (even when molten), and usually are insoluble in water
    5. two examples are diamond and graphite, both made only from carbon atoms
  3. some covalent bonds form simple covalent structures
    1. atoms form very strong covalent bonds forming small molecules of two or more atoms
    2. inter-molecular forces (forces of attraction) are very weak
    3. very low melting and boiling points - atoms are easily parted (weak inter-molecular forces)
    4. usually liquid or gas at room temperature - most simple covalent structures have a 'mushy' appearance - liquid gas or an easily melted solid
metallic structures
1. metal properties are all due to the sea of free electrons
2. the free electrons come from the outer shell of every metal atom in the structure
3. the electrons are free to move so metals are good conductors of heat and electricity
4. the electrons hold the atoms together in a regular structure
5. the electrons allow the atoms to slide over each other causing the metal to be malleable

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