unit 5 section 1 period 3 elements Flashcards
what happens when you react water with sodium(Na) and magnesium(Mg)
(3)
Na - reacts vigorously with cold water and forms a molten ball on the surface. it fizzes and produces the gas H2. forms a strongly alkaline (PH 12-14)
Mg - it reacts very slowly cold water to form a weakly alkaline solution ( PH 9-10 ).
what is the equation for the reaction of sodium with water and also give the equation for the reaction of magnesium with water
(2)
2Na(s) + 2H2O(l) = 2NaOH(aq) + H2(g)
Mg(s) + 2H2O(l) = Mg(OH)2(aq) + H2 (g)
why does magnesium form a weakly alkaline solution when it reacts with water
(1)
this is because Magnesium hydroxide is not very soluble in water, which means not many OH- ions are produced.
what is the equation for the reaction of Mg with steam
(1)
Mg(s) + H2O(l) = MgO(s) + H2(g)
what happens when you react sodium(Na) with oxygen, give the flame colour and the equation
(3)
sodium burns vigorously in oxygen with a orange flame and a solid oxide is formed
2Na(s) + 1/2O2(g) = Na2O
what happens when Mg burns in oxygen, give the flame colour and the equation
(3)
Mg burns vigorously in oxygen with and intense white flame and produces a solid oxide
Mg(s) + 1/2O2(g) = MgO(s)
what happens when you burn aluminium in oxygen, give the flame colour and the equation
(2)
Al burns slowly in oxygen if powdered. if not then an oxide layer forms on the surface which inhibits the reaction. burns a bright white flame
2Al(s) + 3/2 O2(g) = Al2O3(s)
what happens when you burn silicon in oxygen and give the equation
(2)
- if powdered it reacts slowly
Si(s) + O2(g) = SiO2(s)
what happens when you burn phosphorus in oxygen, give the flame colour and the equation
(3)
it burns spontaneously and burns a bright white light and produces a solid oxide
P4(s) + 5O2(g) = P4O10(s)
what happens when you burn sulfur in oxygen, give the flame colour and the equations
(4)
sulfur burns steadily in air( with gentle heating) to produce a blue flame and produces a gaseous oxide
S(s) + O2(g) = SO2(g)
SO2(g) + 1/2O2(g) = SO3(g)
why does MgO, Al2O3 and Na2O all have high melting points
(2)
this is because they all form giant ionic lattices, this means is takes a lot of heat energy to break the bonds and melt them.
why does magnesium oxide have a higher melting point than sodium oxide
(2)
this is because magnesium oxide forms a 2+ ion attracts the O2- ions more strongly than the sodium 1+ ions in sodium dioxide.
why is the melting point of aluminum oxide lower than magnesium oxide
(3)
this is because the difference in electronegativity between the Al and O isn’t as big as the difference in electronegativity of Mg and O. This means that the O2- ions in Al2O3 cannot attract the metal-oxygen bonds as strongly as MgO. this means that the aluminium has covalent character which means that less energy is required to break the bonds.
why does silicon dioxide have a higher melting point than all the other non-metals
(2)
this is because it forms a giant molecular structure, this means strong covalent bonds hold the structure together which means it requires alot of energy to break those bonds
why does P4O10 & SO3 have the lowest melting points in period 3
(2)
this is because they form simple molecular structures, which means the molecules are attached together by weak intermolecular forces ( van der Waals ) which require little energy to overcome.
