Period 3 elements and oxides Flashcards
What are the physical trends across period 3?
Na,Mg and Al- metallic
Si- metalloid
P, S & Cl- non-metal
Ar- noble gas
What type of reaction happens to period 3 elements?
Redox reactions
Which period 3 elements react with cold water?
Na, Mg and Cl
How does Na react with cold water?
Na reacts vigorously, fizzing rapidly producing a strongly alkaline solution(13-14)
How does Mg react with cold water?
Mg reacts very slowly producing a weakly alkaline solution(~10)
Why is Na more reactive than Mg?
It takes less energy to lose one electron than to lose two.
How does Mg react with steam?
Faster reaction
What happens when period 3 elements react with oxygen?
They are oxidised to their highest oxidation states (same as their group numbers) except sulfur.
Why is sulfur an exception when it reacts with oxygen?
SO2 is produced which has a +4 oxidation state
High temperature and a catalyst are needed to make SO3 where sulfur has an oxidation state of +6
How does Na react with oxygen?
It burns with a yellow flame
Vigorous
White Na2O is produced
How does Mg react with oxygen?
It burns with a bright white flame
Vigorous
MgO is produced
How does Al react with oxygen?
Slowly (faster if powdered)
How does Si react with oxygen?
Slowly
How does P react with oxygen?
Red phosphorus must be heated before it reacts with oxygen
White phosphorus spontaneously ignites in air. White smoke is given off
(Red and White P are allotropes)
How does S react with oxygen?
Burns steadily with a blue flame
What are allotropes?
Atoms of the same element arranged differently
What is the bonding and structure in Na2O, MgO and Al2O3?
They have giant ionic lattices and therefore high melting points
It is ionic bonding
Why does MgO have a higher melting point than Na2O?
Mg forms 2+ ions, so the bonds are stronger than 1+ Na ions
Why does that Al2O3 have a lower melting point than expected?
Highly charged Al3+ ions distort the oxygen electron cloud making the bonds partially covalent
What is the bonding and structure in SiO2?
It is covalent bonding
It is a macromolecular structure and therefore a high melting point(strong covalent bonds)
What is the bonding and structure in P4O10 and SO2?
It is covalent bonding
They have simple molecular structures and therefore low melting points(weak intermolecular-van der Waals and dipole-dipole)
Which oxides of period 3 elements are acidic or alkaline?
Ionic oxides are alkaline
Covalent oxides are acidic
What happens when MgO and Na2O react with water?
Hydroxide ions are formed
Both solutions are alkaline
Why does NaOH make a stronger alkaline solution than Mg(OH)2?
NaOH is more soluble in water
What happens when simple covalent oxides- phosphorus and sulfur- react with water?
They form acidic solutions with a pH 0-2
They will dissociate in solution forming hydrogen ions and a conjugate base
Which oxides are insoluble?
Al2O3
SiO2
Why is SiO2 classed as acidic?
It reacts with bases to form salts
Why is Al2O3 amphoteric?
It can act as an acid or a base
Therefore it can react with acids and bases to form salts
Write the equation for the reaction that occurs between amphoteric oxides and sulfuric acid
Al2O3(s) + 3H2SO4(aq) → Al2(SO4)3(aq) + 3H2O(l)
Write the equation for the reaction that occurs between amphoteric oxides,water and sodium hydroxide
Al2O3(s) + 2NaOH(aq) + 3H2O(l) → 2NaAl(OH)4(aq)
What is the equation for the reaction between Mg and water?
Mg(s) + 2H2O(l) → Mg(OH)2(aq) + H2(g)
What is the equation for the reaction between Mg and steam?
Mg(s) + H2O(g) → MgO(s) + H2(g)
What is the equation for the reaction between Na and oxygen?
2Na(s) + 0.5O2(g) → Na2O(s)
What is the equation for the reaction between Mg and oxygen?
Mg(s) + 0.5O2(g) → MgO(s)
What is the equation for the reaction between Al and oxygen?
2Al(s) + 1.5O2 → Al2O3(s)
What is the equation for the reaction between SI and oxygen?
Si(s) + O2(g) → SiO2(s)
What is the equation for the reaction between P and oxygen?
P4(s) + 5O2 → P4O10(s)
What is the equation for the reaction between S and oxygen?
S(s) + O2(g) → SO2(g)
What is the equation for the reaction between Magnesium oxide and water and the pH?
MgO + H2O → Mg(OH)2
pH 9-10
What is the equation for the reaction between Sodium oxide and water and the pH?
Na2O + H2O → 2NaOH
pH 12-14
What is the equation for the reaction between Phosphorus pentoxide and water?
P4O10(s) + 6H2O(l) → 4H3PO4(aq)
What is the equation for the reaction between sulfur dioxide and water?
SO2(g) + H2O(l) → H2SO3(aq)
What is the equation for the reaction between sulfur trioxide and water?
SO3(l) + H2O(l) → H2SO4(aq)
What are the equations for the dissociation of sulfuric acid?
H2SO3(aq) → 2H+(aq) + (SO3)2-(aq)
H2SO4(aq) → 2H+(aq) + (SO4)2-(aq)
What are the equations for the dissociation of phosphoric acid?
H3PO4(aq) → 3H+(aq) + (PO4)3-(aq)
What is the equation for the reaction between magnesium oxide and sulfuric acid?
MgO(s) + H2SO4(aq) → MgSO4(aq) + H2O(l)
What is the equation for the reaction between sodium oxide and hydrochloric acid?
NaO(s) + 2HCl(aq) → 2NaCl(aq) + H2O(l)
What is the equation for the reaction between silicon dioxide and sodium hydroxide?
SiO2(s) + 2NaOH(aq) → Na2SiO3(aq) + H2O(l)
What is the equation for the reaction between phosphorus pentoxide and sodium hydroxide?
P4O10(s) + 12NaOH(aq) → 4Na3PO4(aq) + 6H2O(l)
What is the equation for the reaction between sulfur dioxide and sodium hydroxide?
SO2(g) + 2NaOH(aq) → Na2SO3(aq) + H2O(l)
What is the equation for the reaction between sulfur trioxide and sodium hydroxide?
SO3(g) + 2NaOH(aq) → Na2SO4(aq) + H2O(l)
