Period 3

Question 1

What is the observation for when sodium reacts with water

Answer 1

Forms a molten ball on the surface fizzing and producing H2 gas

Question 2

What is the equation for when sodium reacts with water
What is the pH of the products

Answer 2

2Na(s) + 2H₂O(l) → 2NaOH(aq) + H₂(g)
12-14

Question 3

What is the equation for the reaction between magnesium and water
What is the pH of the products

Answer 3

Mg(s) + 2H2O(l) → Mg(OH)2(s) + H2(g)
9-10

Question 4

Why is the solution produced when water reacts with magnesium only weakly alkaline

Answer 4

Because magnesium hydroxide isn’t very soluble in water

Question 5

What is the reaction for when magnesium reacts with steam

Answer 5

Mg(s) + H₂O(g) → MgO(s) + H₂(g)

Question 6

What is the product for when sodium reacts with oxygen

Answer 6

Na2O (s)

Question 7

What is the product for when magnesium reacts with oxygen

Answer 7

MgO (s)

Question 8

What is the product for when aluminium reacts with oxygen

Answer 8

Al2O3 (s)

Question 9

What is the product for when silicon reacts with oxygen

Answer 9

SiO2 (s)

Question 10

What is the product for when phosphorous reacts with oxygen

Answer 10

P4O10 (s)

Question 11

What is the product for when sulfur reacts with oxygen

Answer 11

SO2 (g)

Question 12

From Na to S what are the reactions in air and the observation

Answer 12

Na - vigorous - yellow flame
Mg - vigorous - brilliant white
Al - slow
Si - slow
P - spontaneously combusts - brilliant white
S - burns steadily - blue

Question 13

Explain the melting points of sodium oxide, magnesium oxide and aluminium oxide

Answer 13

High melting points
Form giant ionic lattices
Strong forces of attraction between negative and positive ions