Chemistry - Bonding Structure & Properties of matter

STRONG Chemical bonds
1. IONIC BONDING
  1. Occurs in compounds formed between METAL & NON- METALS
  2. Particles produced are oppositely charged ions
  3. Only electrons in outer shell of METAL are TRANSFERRED
    1. Metals - LOSE ELECTRONS - become +ly charged ions/ non metals GAIN ELECTRONS- become -ly charged ions
  4. Ions produced by group 1+ 2 metals - and group 6+7 non metals - has electronic structure of NOBLE GAS ( group 0 - full outer shell)
2. METALLIC BONDING
  1. Occurs in metallic ELEMENTS & ALLOYS
  2. Atoms have DELOCALISED electrons
    1. FOUND ON THE OUTER SHELL- delocalised electrons are free to move through WHOLE STRUCTURE
  3. Metals are giant atomic structures arranged in a REGULAR pattern
3. COVALENT BONDING
  1. Atoms SHARE PAIRS of electrons- covalent bonds are STRONG
  2. Occurs in NON metallic elements and compounds of NON elements
  3. Covalent bonded structures - either small molecule, polymers ( large molecules) or giant covalent structures ( i.e diamond/silicon dioxide)
PROPERTIES OF SUBSTANCES
1. Limitations of particle theory-/ simple model - NO FORCES / all particles are shown as SOLID SPHERE
2. STATES SYMBOLS - (s) - solid / (l) liquid / (g) gas/ (aq) aqueous solution - where the solvent is water
3. PROPERTIES OF IONIC COMPOUNDS
  1. Ionic compounds = regular structures/ lattices -have strong electrostatic forces of attraction- in all directions = HIGH BPT + MPT- lots of energy needed to break many strong bonds
  2. Ionic compounds CAN CONDUCT ELECTRICITY when melted or dissolved in water- IONS MOVE & CHARGE CAN FLOW
4. PROPERTIES OF ALLOYS & METALS
  1. Pure metals = are ARRANGED IN LAYERS- so can be BENT/ SHAPED
  2. But PURE METALS - too soft for many uses - so are mixed with OTHER metals - to make HARDER ALLOYS
  3. Alloys have a DISORDERLY ARRANGEMENT due to different size of atoms
  4. METALS AS CONDUCTORS
    1. Metals - good electrical conductors - delocalised electrons can carry electric charge through metal
    2. Metals = good thermal conductors- energy transferred via delocalised electrons
  5. Most metals - have HIGH BPT + MPT - due to srong metallic bonds
5. PROPERTIES OF GIANT COVALENT STRUCTURES
  1. Giant covalent structures = SOLIDS w/ VERY HIGH MPT
  2. Atoms are joined by strong covalent bonds - that need to be overcome to melt/boil substances- i.e carbon allotropes ( silica/diamond)
6. PROPERTIES OF POLYMERS
  1. Polymers - have v. LARGE molecules- the I.M.F( INTERMOLECULAR FORCES) between polymers are STRONG so substances are SOLID at room temp
  2. Atoms in polymers - linked to other atoms via STRONG COVALENT BONDS
7. PROPERTIES OF SMALL MOLECULES
  1. Substamces made up of SMALL molecules - usually GASES/LIQUIDS- low MPT +BPT
  2. Only have week I.M.F forces in between molecules- these IMF and not covalent bonds are broken when substance melt/boils.
  3. Note : IMF increases with SIZE of molecules - larger molecules = higher mpt + bpt
  4. DON'T conduct ELECTRICITY -molecules don't have overall charge
IONIC COMPOUNDS
1. Ionic compound = GIANT structure of ions ( shows IONIC bonding)
2. Held together via Strong ELECTROSTATIC FORCES OF ATTRACTION between oppositely charged ions
3. Electrostatic forces - act is ALL directions -forming a LATTICE
4. EMPIRICAL FORMULA
  1. EXAMPLE- Mg- 2e / Cl+2e - gives the empirical formula of MgCl2
CARBON STRUCTURES/ ALLOTROPES
1. DIAMOND - each carbon atoms forms 4 COVALENT BONDS with other carbon atoms - giant covalent structure- Diamond is VERY HARD/ HIGH MPT/ DOESN'T CONDUCT ELECTRICITY
2. GRAPHITE - carbon atom form 3 COVALENT bonds w/ 3 other carbon atoms- form HEXAGONAL rings - NO COVELENT BONDS BETWEEN LAYERS
  1. Graphite - has 1 DELOCALISED ELECTRON from each carbon atom - so a similar to metals in this way
3. GRAPHENE - single layer of graphite- used in electronics/composites
  1. FULLERENES
    1. Fullerenes are molecules of carbon atoms w/ HOLLOW SHAPES- are made from hexagonal rings of carbona toms - may contain ring with 5 or 7 carbon atoms too - i.e Buckminister Fullerene (C60)- it is a sphere
    2. CARBON NANOTUBES
      1. ARE CYLINDRICAL fullerenes - have a HIGH length to diameter ratio - properties make them USEFUL for nanotechology/materials/electronics/cosmetics/catalysts
        (NANO PARTICLES) Approx.1-100nm in diameter- so have higher SA:VOL ratio - smaller quantities are needed for it to be effective than normal size particles
LIMITATIONS OF DOT + CROSS/ BALL AND STICK DIAGRAMS
1. Ball + stick - pros - shows charges on ions/ numer of atoms / 3D arrangement/ cons - ions are closer together/ false image of bond direction
2. Melting & freezing happen at mpt / boiling and condensing happen at bpt
3 STATES OF MATTER
1. The energy required to change states - depends on strength of forces between particles and type of bonding/strucutrw - stronger bonging/forces = higher bpt & mpt

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