3.2.4 - Period 3 elements

Question 1

Why is sodium more reactive than magnesium?

Answer 1

Takes less energy for Na to lose one electron compared to Mg to lose two electrons

Question 2

Why is the melting point of silicon oxide higher than that of phosphorus oxide? (4)

Answer 2

• SiO2 has a giant covalent structure
• Strong covalent bonds require lots of energy to break
• P4O10 is simple covalent molecule
• Weak VdW between molecules break easily

Question 3

State the two equations for the reactions of the ionic oxides with water

Answer 3

• Na2O + H2O → 2NaOH
• MgO + H2O → Mg(OH)2

Question 4

What do the ionic oxides form when reacting with water?

Include their respective pHs

Answer 4

• Alkaline solutions
• Na2O forms NaOH (12-14)
• MgO forms Mg(OH)2 (9-10)

Question 5

What do non-metal oxides form when added to water?

Answer 5

Acid

Question 6

Why does Na2O form an alkaline solution?

Answer 6

• Contains O2- ions
• React with water to form OH- ions

Question 7

State the equation for the reaction of phosphorus oxide with water

Answer 7

P4O10 + 6H20 → 4H3PO4

Question 8

State the equation for the reaction of sulphur dioxide with water

Answer 8

SO2 + H2O → H2SO3

Question 9

State the equation for the reaction of sulphur trioxide with water

Answer 9

SO3 + H2O → H2SO4

Question 10

State the equation when aluminum oxide is added to HCl

Answer 10

Al2O3 + 6HCl —> 2AlCl3 + 3H2O

Question 11

State the equation when aluminum oxide is added to NaOH (base)

Answer 11

Al2O3 + 2NaOH + 3H2O —> 2Na[Al(OH)4]-

Question 12

Name the two insoluble compounds

Answer 12

• Al203 (amphoteric)
• SiO2 (acidic)

Question 13

Give the acid base reaction equation

Answer 13

Acid + base = salt + water

Question 14

What are two observations when sodium burns in oxygen?

Answer 14

• Yellow flame
• White solid