I2: 22 Periodicity Flashcards
What is the reaction of Na with water?
2Na (s) + 2H2O (l) -> 2NaOH (aq) + H2 (g)
Na reacts vigorously with water, forming a molten ball on the surface, fizzing and producing H2 gas bubbles.
Produces NaOH so creates a strongly alkaline solution (ph 13-14)
What is the reaction of Mg with water?
Mg (s) + 2H2O (l) -> Mg(OH)2 (aq) + H2 (g)
Mg reacts very slowly with water (a few bubbles are produced), forming a weakly alkaline solution (ph 9-10). Magnesium hydroxide is not very soluble in water so few hydroxide ions are released.
Mg (s) + H2O (g) -> MgO (s) + H2 (g)
Mg reacts much faster with steam.
What is the reaction of Na with oxygen?
4Na (s) + O2 (g) -> 2Na2O (s)
Burns brightly with yellow flame and a white solid produced.
What is the reaction of Mg with oxygen?
2Mg (s) + O2 (g) -> 2MgO (s)
Burns brightly with a white flame and a white powder produced.
What is the reaction of Al with oxygen?
4Al (s) + 3O2 (g) -> 2Al2O3 (s)
Slow reaction but faster when in powdered form (there’s no coating of Al2O3)
Burns brightly and a white powder produced.
What is the reaction of Si with oxygen?
Si (s) + O2 (g) -> SiO2 (s)
Slow reaction.
What is the reaction of P with oxygen?
P4 (s) + 5O2 (g) -> P4O10 (s)
Extremely exothermic, spontaneously combusts.
What is the reaction of S with oxygen?
S (s) + O2 (g) -> SO2 (g)
S (s) + O2 (g) -> SO3 (l)
SO2 burns steadily with a blue flame.
What is the trend in melting points of the oxides of Na-S?
Na2O, MgO, Al2O3, and SiO2 have high melting points.
This is because Na2O, MgO and Al2O3 are giant ionic lattices. There is strong electrostatic attraction between oppositely charged ions.
MgO has a higher melting point than Na2O because Mg2+ ions are smaller and higher charged so bonds more strongly.
Al2O3 has a lower melting point due to some covalent character due to the polarising nature of Al3+ ions.
SiO2 has a higher melting point because it is macromolecular and has strong covalent bonds.
P4O10, SO2, and SO3 have low melting points because they are simple molecular and have weak intermolecular forces (dipole-dipole and van der Waals).
What is the reaction of Na2O with water?
Na2O (s) + H2O (l) -> 2NaOH
Dissolves in water and the O2- ions accept protons from the water molecules to form OH- ions, forming a strongly alkaline solution (pH 12-14).
What is the reaction of MgO with water?
MgO (s) + H2O (l) -> Mg(OH)2 (aq)
Dissolves less in water and the O2- ions accept protons from the water molecules to form OH- ions, forming an alkaline solution (pH 9-10).
What is the reaction of Al2O3 with water?
Insoluble in water due to its partially ionic and covalent nature.
What is the reaction of SiO2 with water?
Insoluble in water due to its macromolecular structure.
What is the reaction of P4O10 with water?
P4O10 (s) + 6H2O (l) -> 4H3PO4 (aq)
H3PO4 (aq) -> 3H+ (aq) + PO43- (aq)
Forms strongly acidic solution (pH 1-2) and will dissociate, forming H+ ions and a PO43- ion.
What is the reaction of SO2 with water?
SO2 (g) + H2O (l) -> H2SO3 (aq)
H2SO3 (aq) -> 2H+ (aq) + SO32- (aq)
Forms acidic solution (pH 2-3) and will dissociate, forming H+ ions and a SO32- ion.
