Periodicity

Nota:

• -Elements are arranged in order of increasing size

1. Group

   Nota:

   • -vertical column -each group shares chemical properties -group number indicates number of valence electrons
2. Period

   Nota:

   • -horizontal row -period indicates number of electron shells

1. Atomic Radius

   Nota:

   • -decrease across period -increase down group -occurs due to shielding effect
   1. Shielding Effect

      Nota:

      • =a reduction in the effective nuclear charge on the electron cloud, due to a difference in the attraction forces of the nucleus on its valence electrons -The greater the shielding effect, the less electron attraction and the lower the ionisation energy
2. Ionic Radius

   Nota:

   • -increase down -decrease (staggered) across
   1. Cations

      Nota:

      • -decrease compared to atoms -decrease across period
   2. Anions

      Nota:

      • -increase compared to atom -decrease across period
3. Ionization Energy

   Nota:

   • -the minimum energy needed to remove an electron from 1 mol of gaseous atoms -is positive as it's an endothermic process -depends on: distance between electrons and nucleus, size of the positive nuclear charge by inner electrons and the shielding effect from the nuclear charge -the greater the ionisation energies in an atom, the more stable the electron configuration
4. Electronegativity

   Nota:

   • -The ability for an atom to attract a bonding pair of electrons, measured relative to fluorine -increase across as radius decreases across and positive nuclear charge increases -decrease down as no.main energy levels increases
5. Melting Points

   Nota:

   • -depends on structure of element and type of attractive forces holding the atom together -G1,G2, G3: metallic bond, high melting point, increases across -G4: macromolecular covalent, very strong bond, high melt -G5, G6, G7: simple molecular covalent+weak van der Waals', low melt -G8: monatomic molecules, very weak bonds, very low melt

Nota:

• -Groups share the same chemical properties

1. Group 7 - Halogens

   Nota:

   • -react by gaining an electron to form halide ions -good oxidising agents -decrease in reactivity down group -can displace other halide ions if they're more reactive -Test for halide ions: add silver nitrate to form precipitate.  chlorine-white bromine-cream iodine-yellow
2. Group 1 - Alkali Metals

   Nota:

   • -Reactivity increases down group -react by losing single valence electron -good reducing agents -react with water to form alkali solution of metal hydroxide and hydrogen gas -react with halogens to form ionic salts -have different reactions with water, increasing in intensity as you go down the group
3. Metallic to Non-metallic

   Nota:

   • -metals: shiny, good conductors -G1,G2,G3: good metals -G4: semi-conductor, METALLOID -G5, G6, G7, G8: non-metals -Metal oxides = basic -Non-metal oxides = acidic -Aluminium = amphoteric

1. Oxides

   Nota:

   • -Solid to Liquid(2) -Melt: Increase then decrease (turns at Aluminium) -Boil: increase then decrease (highest at MgO) -Electrical: Good(3) to Bad(4) -Structure: ionic(3) to covalent molecular -react with water: alkali(2) to no reaction(2) to acidic solution made(3) -nature: basic(2) - amphoteric(1) - acidic(4)
2. Chlorides

   Nota:

   • -State: solid(3) to liquid(3) to gas(1) -Melt: decreasing across -Boil: decreasing (nothing at Al) -Electrical: Good(2) to Poor(1)/None(4) -Structure: Ionic(2) to Simple Covalent Molecular(5) -Reaction with H2O: Dissolve(2) to Produce HCl Fumes(4) to some reaction with water(1) -Nature: Neutral(1) to weak acid(1) to acidic(5)
3. First Ionization Energy

   Nota:

   • -ionisation energy increases across period as more energy is needed to remove the electrons -decreases down Groups 1&7

Nota:

• -a d-block element that forms at least one stable ion that has a partially filled d-sub-level -characteristics: variable oxidation states, have catalytic properties, make coloured compounds and form complex ions

1. Complexes

   Nota:

   • central metal ion surrounded by a number of other molecules or ions; formed usually when transition metals are dissolved water or become hydrated
   1. Ligands

      Nota:

      • A molecule or a negative, which contains a lone pair of electrons which it uses to form a dative bond with the central ion in a complex
      1. Coordination Number

         Nota:

         • The number of ligands that are attached to a metal ion
2. Coloured Compounds
3. Variable Oxidation States

   Nota:

   • -when transition elements lose electrons, they lose 4s electrons first -all have transition state of +2 -ionization energies determines the loss of additional electrons from 3d-sub-shell
4. Catalytic Behaviour
   1. Catalst
      1. Heterogeneous Catalyst

         Nota:

         • Catalyst is in a different phase from reactants (doesn't take part in the reaction)
      2. Homogeneous Catalyst

         Nota:

         • Catalyst is in the same phase as the reactants (can take part in the reaction)