Period 3 and their oxides Flashcards
Describe the general pattern of first ionisation energies across period 3
Generally increases, though decreases from:
Mg to Al
P to S
A period 3 element reacts with cold water to produce hydrogen gas and a hydroxide. Which element is it?
Na
A period 3 element reacts with cold water to produce hydrogen gas and a hydroxide, but only very slowly. Which element is it?
Mg
Mg reacts with cold water to produce hydrogen gas and a hydroxide. When it reacts steam, the products are slightly different. What are they?
MgO and hydrogen Gas
Give an equation to show the reaction between Na and cold water
2Na (s) + 2H2O (l) –> 2NaOH (aq) + H2 (g)
Is the reaction between Na and cold water fast or slow?
Fast
Is the reaction between Mg and cold water fast or slow?
Very slow
Give an equation to show the reaction between Mg and cold water
2Mg (s) + 2H2O (l) –> 2Mg(OH)2 (aq) + H2 (g)
Give an equation to show the reaction between Mg and steam
Mg (s) + H2O (g) –> MgO (s) + H2 (g)
What is formed when period 3 elements react with oxygen?
Their oxides
An element is reacted with oxygen. It burns with a yellow flame to produce a white solid. What is the element?
Na
An element is reacted with oxygen. It burns with a white flame to produce a white solid smoke. What is/are the elements?
Mg, Al, Si and P
An element is reacted with oxygen. It burns with a blue flame to produce an acidic choking gas. What is the element?
S
Give an equation to show the reaction of O2 and Na
4Na (s) + O2 (g) –> 2Na2O (s)
Give an equation to show the reaction of O2 and Mg
2Mg (s) + O2 (g) –> 2MgO (s)
Give an equation to show the reaction of O2 and Al
4Al (s) + 3O2 (g) –> 2Al2O3 (s)
Give an equation to show the reaction of O2 and Si
Si + O2 (g) –> SiO2 (s)
Give an equation to show the reaction of O2 and P
4P + 5O2 (g) –> P4O10 (s)
Give an equation to show the reaction of O2 and S
S + O2 (g) –> SO2 (g)
Sodium and phosphorous will react with air to form their oxides. How are they stored to prevent this?
Na in oil
P under water
Describe and explain which oxide out of P4O10 and SO2 has the higher melting point
P4O10 has the higher melting point
Bigger molecule and so will have larger Van der Waals forces
Why does aluminium metal not corrode?
It is protected by a thin layer of Al2O3 (s)
It has a high lattice strength and is insoluble, so is impermeable to air and water
Give an equation to show the reaction between water and Na2O
Na2O + H2O –> 2Na+ (aq) + 2OH- (aq)
Give an equation to show the reaction between water and MgO
MgO + H2O –> Mg(OH)2 (s)
Give an equation to show the reaction between water and Al2O3
Doesn’t react
Ionic lattice too strong
Give an equation to show the reaction between water and SiO2
Doesn’t react
Macromolecular structure - strong covalent bonds
Give an equation to show the reaction between water and P4O10
P4O10 + 6H2O –> 4H3PO4 (aq)
Give an equation to show the reaction between water and SO2
SO2 +H2O –> H2SO3 (aq)
Give an equation to show the reaction between water and SO3
SO3 + H2O –> H2SO4
A metal oxide reacts with water to give product(s) with pH 13. What is the metal oxide?
Na2O
A metal oxide reacts with water to give product(s) with pH 9. What is the metal oxide?
MgO
Both MgO and Na2O react with water to give alkaline products. However, the pH of the MgO product is pH9, whilst the pH of the Na2O product is pH13. Why is MgO’s lower?
MgO has a higher lattice strength, and so is only slightly soluble in water. This means fewer free OH- ions are produced
A metal oxide reacts with water to give product(s) with pH 0. What is/are the metal oxides?
P4O10 and SO3
A metal oxide reacts with water to give product(s) with pH 3. What is the metal oxide?
SO2
Give an equation to show the ions formed in solution when SO2 reacts with water
SO2 + H2O –> H+ + HSO3-
Give an equation to show the ions formed in solution when SO3 reacts with water
SO3 + H2O –> H+ + HSO4-
Al2O3 is amphoteric. Give two ionic equations to show this
Al2O3 + 6H+ –> 2Al3+ + 3H2O (as an acid)
Al2O3 + 2OH- + 3H2O –> 2Al(OH)4- (aq)
