Chemistry: Bonding structure and properties of matter

Chemistry: Bonding structure and properties of matter

1. Ions

   • Made when electrons are transferred
     • charged particles are ions, such as Cu2+
       • Metals lose electrons to form positive ions
         • Non metals gain electrons to form negative Ions
     • When a non Metal and Metal react the metal loses an electron whilst the non metal gains electrons
       • Oppositely charged ions are attracted together by strong electrostatic forces
         • group 1,2 and 6,7 are most likely to form ions
           • e.g. group 6 elements form -2 ions (as they gain 2 electrons
             • IMPORTANT: ionic bonds Can be represented by cross and dot diagrams
     • Ionic Bonding
   • Ionic Bonds occur between Metals and non Metals (metal loses electrons non metal gains)
     • Covalent bonding occurs between two non metals (molecules) this is where electrons are shared
   • Ionic Compounds
     • Ionic Compounds have a GIANT IONIC LATTICE STRUCTURE
       • Very strong electrostatic forces between ions
         • Ionic structures have high Melting and Boiling points
           • They don't conduct electricity when solid, but do when melted and dissolved in water as ions can move freely

2. Covalent Bonding

   • The SHARING of electrons (Only in outer Shell)
     • When Non-Metal atoms bond they share electrons to form Covalent bonds
       • Covalent bonds are very strong due to the strong electrostatic force between the positively charged nucleus and Shared electrons
         • Covalent bonds often mean the atoms have full outer shells
           • This makes them very stable (they are now a noble gas)
     • Each single covalent bond provides one electron
   • Drawing Covalent Bonds
     • Use dot and cross diagrams
       • Draw electrons Overlapping between outer orbitals of two atoms
         • These are useful as show which electrons have come from the covalent bonding
           • e.g.
             • Here hydrogen is sharing an electron with another hydrogen atom to make H2.
               • Or the bonding of Methane (REMEMBER METHANE IS COVALENT AS TWO NON METALS ARE BONDING)
                 • e.g.

3. Polymers (Long Chain of monomers)

   • Polymers are essentially REPEATING UNITS
     • All atoms in a polymer are joined by strong COVALENT bonds (Non metal bonding - sharing)
       • We draw polymers by the smallest repeating unit:
         • Like this:
           • Double bond opens up
             • The 'n' on the right shows it is a repeating unit
               • We can use it to find the molecular formula (Not so important)
   • Intermolecular forces between polymer molecules is larger than simple covalent molecules (so needs more energy to break them
     • However their intermolecular forces aren't as strong as IONIC or COVALENT bonds (So lower boiling and melting points

4. Giant Covalent Structures

   • Giant covalent structures are macromolecules
     • All atoms are bonded by strong covalent Bonds (sharing, non metals)
       • Very HIGH melting and boiling points as a lot of energy is needed to break bonds
         • They do not contain charged particles (Ions) so DO NOT conduct electricity
           • Main examples are:
             • Diamond (EACH CARBON ATOM FORMS 4 COVALENT BONDS)
               • Silicon Dioxide (What sand is Made of)
                 • each giant structure of silicon and oxygen is a grain of sand
                 • And Graphite (DOES CONDUCT ELECTRICITY)
                   • Each carbon atom forms 3 covalent bonds, forming layers of hex(5)agons
                     • BUT - each carbon atom also has one delocalised electrons (so graphite conducts electricity)
                       • Allotropes of Carbon
                         • ALLOTROPES ARE DIFFERENT STRUCTURAL FORMS OF THE SAME ELEMENT IN THE SAME PHYSICAL STATE
                           • E.G. Diamond
                             • Diamond is made up of carbon atoms that form 4 covalent bonds.
                               • It has a high melting point due to strong COVALENT bonds
                                 • It doesn't conduct Electricity
                           • E.G. graphite
                             • Each carbon atom forms 3 COVALENT bonds
                               • ONLY 3 of carbons 4 outer electrons are used in bonding, so one is delocalised (MEANING GRAPHITE CONDUCTS ELECTRICITY)
                               • Can be used for lubrication as in layers (so soft and slippy)
                                 • BECAUSE BONDS ARE HELD WEAKLY
                             • High melting point as strong bonds
                           • E.G. Graphene
                             • ONE LAYER OF GRAPHITE
                               • SHEET OF CARBON ATOMS JOINED IN HEXAGONS
                                 • one atom thick (two dimensional compound)
                                   • Network of covalent bonds make it very strong (but also very light)
                                   • Also conducts electricity like Graphite due to DELOCALISED ELECTRONS
                                     • SO COULD BE USED IN ELECTRONICS
                         • This diagram is missing Metallic Bonding, fullerenes and States of matter (revise these if needed)

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