period 3 3.2.4 in papers 2 + 3
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describe the structure and bonding in period 3
• Na & Mg = metallic bonding • Si = macromolecular + covalent bonding • P & S & Cl = simple molecular + covalent bonding • Ar = monoatomic + no bonding
describe melting and boiling points across period 3
• Na & Mg & Al have high mpt due to strong electrostatic forces of attraction between positively charged ions and delocalised electrons • Si has a high bpt due to many strong covalent bonds • P & S & Cl have low bpt due to weak intermolecular forces between the molecules
describe the electrical conductivity across period 3
Na, Mg & Al all conduct electricity due to delocalised electrons that carry the charge
describe the atomic radius across period 3
• as you go across, atomic radius decreases • due to strong attraction between the nucleus and outer electron • shielding stays the same
describe the ionisation energy across period 3
• it generally increases because shielding remains the same while the number of protons increases • Al & S are differerent because an electron in Al is removed from the 3p orbital which has lower ionisation energy • S electron is removed from a paired electron, electron pair repulsion makes it easier to remove
what elements in period 3 reat with water?
Na Mg Cl
what happens when sodium reacts with water?
• reacts vigorusly • rapidly melts due to heat given off • fizzes on surface • strong alkaline solution formed 2Na + 2h2O -> 2NaOH + H2
what happens when Mg reacts with water?
• reacts very slowly • less alkaline because Mg(OH)2 is slighlty soluble • reaction is faster when heated and steam is used to produce MgO
what happens when Na reacts with oxygen?
• burns brightly • orange flame • 2Na + 1/2O2 -> Na2O • ionic bonding • ionic lattice • alkaline
what happens when Mg reacts with oxygen?
• burns brightly to give a white flame • white solid remaining is MgO • Mg + 1/2O2 -> MgO • ionic • ionic lattice • alkaline
what happens when silicon reacts with oxygen?
• forms and oxide when strongly heated • Si + O2 -> SiO2 • covalent bonding • macromolecular • weakly acidic
what happens when phospurus reacts with oxygen?
• white P spontaneosly ignites with air • white smoke produced is phosphorus pentoxide • 4P + 5O2 -> P4010 • covalent bonding • simple molecular • acidic
what happens when sulphur reacts with oxygen?
• S + O2 -> SO2 • S + 3/2O2 -> SO3 • covalent bonding • simple molecular • acidic
what happens when Al reacts with oxygen?
• burns brightly • white solid remaining is Al2O3 • ionic bonding with covalent character • ionic lattice • amphoteric
which oxides are basic?
• Na2O • MgO
which oxides are insoluble?
• Al2O3 • SiO2
which oxides are acidic?
• P4O10 • SO2 • SO3
what are the equations when period 3 oxides react with water?
• Na2O + H2O -> 2NaOH • MgO + H2O -> Mg(OH)2 • P4O10 + H2O -> 4H3PO4 • SO2 + H2O -> H2SO3 ( sulfurous acid) • SO3 + H2O -> H2SO4
what are the equations for when period 3 oxides react with acids or bases?
• Na2O + H2SO4 -> Na2HSO4 + H2O • MgO + H2SO4 -> MgSO4 + H2O • Al2O3 + 6HCl -> 2AlCl3 + 3H2O • Al2O3 + 2NaOH -> 3H2O + 2NaAl(OH)4 • SiO2 + 2NaOH -> Na2SiO3 + H2O • P4O10 + 3NaOH -> Na3PO4 + 3H2O • SO2 + NaOH -> NaHSO3
what test distinguishes MgCl2 and AlCl3 and what is observed?
• NaOH • MgCl2 = white percipitate • AlCl3 = white percipitate that dissolves in excess
what test distinguishes P4O10 and Na2O and what is observed?
• add h2o • add litmus paper • p4o10 turns red • na2o turns blue