Unit 2: Section 3 - Period 3 Elements Flashcards
Is sodium or magnesium more reactive? Why?
Sodium is more reactive because it takes less energy for it to lose an electron than it does to lose two electrons, which is what magnesium has to do.
What happens during the reaction between sodium and cold water? (inc. equation)
Sodium reacts vigorously, forming a molten ball on the surface, fizzing and producing H2 gas. The solution produced if very alkaline.
2Na(s) + 2H2O(l) –> 2NaOH(aq) + H2(g)
What happens during the reaction between magnesium and cold water? (inc. equation)
Magnesium reacts very slowly, producing a thin coating of magnesium hydroxide on the surface of the metal and a slightly alkaline solution (very few hydroxide ions are formed as magnesium hydroxide isn’t very soluble).
Mg(s) + 2H2O(l) –> Mg(OH)2(aq)
What happens during the reaction between magnesium and steam? (inc. equation)
Magnesium reacts much faster with steam as there is more energy available.
Mg(s) + H2O(g) –> MgO(s) + H2(g)
How do you know the elements highest oxidation state?
It’s the same as their group number.
What happens when period 2 oxides react with oxygen? What is the exception?
They form oxides which have their highest oxidation state.
Except for sulphur which forms SO2 (ox +4) and needs a higher temperature and a vanadium catalyst to form So3 (ox +6)
Which period 3 elements react the most readily in the air?
Na (vigorous), Mg (vigorous), S (steady burn), P (spontaneously combusts)
Describe and explain the trend in melting points of period 3 oxides.
The trend is decreasing down the group however sodium oxide is lower than magnesium oxide. This is because Mg forms 2+ ions which bond more readily than the 1+ ions in Na.
SiO2 than the other non-metals because it has a giant macromolecular structure, with strong covalent bonds which require a lot of energy to break.
Other non-metals have simple structures, bound by weak intermolecular forces, which take little energy to break.
_____ oxides are alkaline, _____ oxides are acidic
ionic
covalent
What happens when sodium oxide and magnesium oxide reacts with water? Why? (inc. equations)
They are ionic oxides so they produce an alkaline solution. This is because they contain oxide ions (O2-), which will accept proteins from the water to form hydroxide ions (OH-).
NaOH is more soluble in water so it is more alkaline.
Na2O(s) + H2O(l) –> 2NaOH(aq) {pH = 12 - 14}
MgO(s) + H2O)(l) –> Mg(OH)2(aq) {pH = 9 - 10}
What happens when phosphorus oxide and sulphur dioxide reacts with water? Why? (inc. equations)
They are covalent oxides so they produce an acidic solution. This is because they dissociate in solution, forming hydrogen ions and a negative ion, sometimes called a conjugate base.
P4O10(s) + 6H2O(l) –> 4H3PO4(aq) {phosphoric acid}
H3PO4(aq) –> 3H+(aq) + PO43-(aq)
SO2(g) + H2O(l) –> H2SO3aq) {sulphurous acid}
H2SO3(aq) –> 2H+(aq) + SO32-(aq)
SO3(l) + H2O(l) –> H2SO4aq) {sulphuric acid}
H2SO4(aq) –> 2H+(aq) + SO42-(aq)
How is aluminium oxide different from the other metal oxides in period 3? (2)
Aluminium oxide has both ionic and covalent bonds. This is because there isn’t a large difference in electronegativity between aluminium and oxygen. This means the oxygen ions in aluminium oxide don’t attract the electrons in the metal-oxygen bond as strongly.
Aluminium oxide is amphoteric so it can act as an acid or a base.
What happens when aluminium oxide reacts with water? Why?
Nothing as aluminium oxide is insoluble in water.
What happens when silicon dioxide reacts with water? Why?
Nothing as silicon dioxide is insoluble in water due to its giant covalent structure.
What is the equation for neutralising an acid?
Acid + Base –> Salt + Water
