Chemistry: Period 3 Part 2
Overall Description: This flashcard set categorizes elements based on their atomic structures. It identifies metals like Na, Mg, and Al as forming giant lattices, silicon as macromolecular, nonmetals like P₄, S₈, and Cl₂ as simple covalent molecules, and noble gas argon as monoatomic.
why does SiO2 have a higher melting point than P4O10
SiO2 macromolecular and P4O10 is simple molecular
| strong covalent bonds in SiO2 require more energy to break than weak VDW forces between P4O10 molecules
Key Terms
why does SiO2 have a higher melting point than P4O10
SiO2 macromolecular and P4O10 is simple molecular
| strong covalent bonds in SiO2 require more energy to break than weak VDW forces between P...
why does P4O10 have a higher melting point that SO3
P4O10 larger molecules-more electrons than SO3
| - p4o10 stronger VDW forces between molecules- more energy to break
in general, what do metal oxides from period 3 elements react with water to form
solutions containing hydroxide ions
sodium oxide and water equation
Na2O + H2O > 2NaOH
pH of resulting solution Na2O and H2O
Na2O is soluble and resulting solution has pH 11-14
magnesium oxide and water equation
MgO + H2O > Mg(OH)2
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| Term | Definition |
|---|---|
why does SiO2 have a higher melting point than P4O10 | SiO2 macromolecular and P4O10 is simple molecular | strong covalent bonds in SiO2 require more energy to break than weak VDW forces between P4O10 molecules |
why does P4O10 have a higher melting point that SO3 |
| - p4o10 stronger VDW forces between molecules- more energy to break |
in general, what do metal oxides from period 3 elements react with water to form | solutions containing hydroxide ions |
sodium oxide and water equation | Na2O + H2O > 2NaOH |
pH of resulting solution Na2O and H2O | Na2O is soluble and resulting solution has pH 11-14 |
magnesium oxide and water equation | MgO + H2O > Mg(OH)2 |
pH of resulting solution MgO and H2O | sparingly soluble- pH 8-10 |
is Al2O3 soluble in water | no- pH remains 7 |
what do non metal oxides of period 3 elements react with water to form | solutions containing H+ ions |
SiO2 and water solubility? | insoluble- sand |
P4O10 and water equation | P4O10 + 6H2O > 4H3PO4 |
pH of resulting solution P4O10 and WATER | 1-2- STRONG ACID |
SO2 and water equation | SO2 + H2O > H2SO3 |
pH of resulting solution SO2 and water | 2-4- weak acid |
equation SO3 and water | SO3 + H2O > H2SO4 |
pH of resulting solution SO3 | 0-2 |
examples of ionic oxides | Na2O and MgO |
what do ionic oxides react with acids to form and why | salt and water they are basic |
equation sodium oxide and sulphuric acid | Na2O + H2SO4 > Na2SO4 + H2O |
equation magnesium oxide and hydrochloric acid | MgO + 2HCl > MgCl2 + H2O |
examples of covalent oxides | SiO2, P4O10, SO2, SO3 |
what do covalent oxides react with aqueous alkali to form and why | salt and water- theyre acidic |
equation silicon oxide and sodium hydroxide | SiO2 + NaOH > Na2SiO3 + H2O |
equation phosphorus (v) oxide and sodium hydroxide | P2O5 + 6NaOH > 2Na3PO4 + 3H2O |
equation sulphur (IV) oxide and sodium hydroxide | SO2 + NaOH > Na2SO3 + H2O |
equation sulphur (VI) oxide and sodium hydroxide | SO3 + NaOH > Na2SO4 + H2O |
why does aluminium react with both acids and bases | its amphoteric |
equation aluminium oxide and hydrochloric acid | Al2O3 + 6HCl > 2AlCl3 + 3H2O |
equation aluminium oxide and nitric acid | Al2O3 + 6HNO3 > 2Al(NO3)3 + 3H2O |
equation aluminium oxide and sodium hydroxide | Al2O3 + 2NaOH + 3H2O > 2NaAl(OH)4 |
what do aluminium salts form when dissolved in water | acidic solutions |
why do aluminium salts form acidic solutions when dissolved in water | the ionic lattice breaks down and the Al3+ ions become surrounded by water forming a hexaaqua ion |
hexaagua ion | [Al(H2O)6]3+ |
how many water molecules is the Al3+ ion surrounded by | 6 |
how is each water molecule bonded to the aluminium ion | coordinate bond |
what does the charge on the Al3+ ion cause the electron density in the water molecule to do | move closer to the metal ion- water molecule polarised |
what does the Al3+ ion have enough polarising power to do | weaken the OH bonds in water- one of bonds breaks and a proton donated |
equation for hexaagua ion losing proton | [Al(H2O)6]3+ > [Al(H2O)5(OH)]2+ + H+ |
what does adding a base to an aqueous solution of the hexaaqua aluminium ion produce | an insoluble precipitate of aluminium hydroxide |
equation for hexaaqua ion and hydroxide ion | [Al(H2O6)]3+ + OH- > [Al(H2O)5(OH)]2+ + H2O |
what happens to the equilibrium if you add more OH- ions to the hexaaqua aluminium ion | shifts to RHS to oppose change and reduce OH concentration and a new equilibrium is set up |
what new equilibrium is set up when more OH- ions are added to alumium hexaaqua ions | [Al(H2O)5(OH)]2+ + OH- <> [Al(H2O4)(OH2)]+ + H2O |
what final equilibrium is set up when even more OH- ions are added to aluminium hexaaqua ion | [Al(H2O)4(OH2)]+ + OH- <> [Al(H2O)3(OH)3] + H2O |
why is the white precipitate formed from the final equilibrium of aluminium hexaaqua ion insoluble and why does it precipitate out | its neutral |
overall equation for equilibrium of hexaagua ion | [Al(H2O)6]3+ +3OH- > [Al(H2O)3(OH3)] + 3H2O |
amphoteric | species that can act as an acid or base |
equation aluminium hydroxide reacting with acid | [Al(H2O)3(OH)3] + H+ > [Al(H2O)6]3+ | simplified: Al(OH3) + H+ > Al3+ + 3H2O |
what does the white precipitate of aluminium hydroxide dissolve to form | colourless solution |
equation aluminium hydroxide reacting with base | [Al(H2O)3(OH)3] + OH- > [Al(H2O)2(OH)4]- + H2O | simplified: Al(OH)3 + OH- > Al(OH)4- |