Period 3 elements

Question 1

Why does Mg have a higher melting point than Na

Answer 1

Both are Giant metallic structures
Magnesium ions have a higher charge density
The are more delocalised electrons in magnesium
stronger electrostatic attraction between positive ions and the delocalised electrons

Question 2

Why does silicon have a higher melting point than phosphorus

Answer 2

Silicon is macromolecular with strong covalent bonds while phosphorus is simple molecular with weak vdw forces between molecules
Strong covalent bonds require a lot of energy to overcome

Question 3

Why does sulfur have a higher melting point than phosphorus

Answer 3

sulfur has more molecules (8) within the atom than phosphorus(4)
Greater vdw hence more energy needed to overcome

Question 4

Reaction of Sodium with water equation
observation
product

Answer 4

2Na(s) + 2H2O(l) —> 2NaOH(aq) + H2(g)
Hydrogen has produced Exothermic
Colourless alkali solution

Question 5

Reaction of Magnesium with cold water
Equation
Observation
Product

Answer 5

Mg(s) + 2H2O(l) —> Mg(OH)2(s) + H2
Minor bubbles(slow reaction)
Sparingly soluble|weakly alkaline solution

Question 6

Reaction of magnesium with steam
Equation
Observation
Thought

Answer 6

Mg(s) + 2 H2O(l) ——> Mg(OH)2(s) + H2(s)
White flame|White sold (fast reaction)
Basic solid

Question 7

Reaction of Sodium with oxygen
Equation
Observation

Answer 7

2Na + 1/2O2 —-> Na2O(s)
Yellow flame(or orange)
Yellow solid(Reacts readily in air)

Question 8

Reaction of Magnesium and oxygen
Equation
Observation

Answer 8

Mg(s) + 1/2O2(s) —-> MgO(s)
White flame
White solid(reacts readily in air)

Question 9

Reaction of aluminium and oxygen

Answer 9

2Al(s) + 3/2O2(g) —-> Al2O3(s)
Reacts slowly

Question 10

Reaction of silicon and oxygen
Equation
Observation

Answer 10

Si(s) + O2(g) —-> SiO2(s)
Reacts slowly

Question 11

Reaction of Phosphorus and Oxygen
Equation
Observations

Answer 11

4P + 5O2 —-> P4O10(s)
White solid
White flame

P4 reacts spontaneously in air so is stored in oil or under water

Question 12

Reaction of Sulfur and oxygen
equation
observations

Answer 12

S(s) + O2(g) —-> SO2(g)
Blue flame
choking gas(SO2)
Reacts readily in air

Question 13

Which period 3 oxides act as a base why and name their structure and bonding

Answer 13

Na2O MgO because they are metals
GIANT IONIC LATTICE
ionic bonding

Question 14

Which period 3 oxides act as acids and why and name the bonding and structures

Answer 14

SiO2(macromoleculer)
SO2 (simple molecular)
P4O10 (simple molecular)
Covalent bonding
Because they are non-metals

Question 15

Which period 3 oxides is amphoteric and name its structure and bonding

Answer 15

Al2O3
Ionic bonding
GIANT IONIC LATTICE

Question 16

Name the typical pH of the metal oxides in period 3 and their solubility in water

Answer 16

Na2O pH:14 Soluble
MgO pH:10 sparingly
Al2O3 pH:n/a no

Question 17

Name the typical pH of the non-metal oxides in period 3 and their solubility in water

Answer 17

SiO2 pH:n/a Not soluble
P4O10 pH:1-2 Soluble
SO3 pH:0 Soluble
SO2 pH:1-2 Soluble

Question 18

Equations for Na2O and MgO with water

Answer 18

Na2O(s) + H2O(l) —-> 2NaOH
MgO(s) + H2O(l) —-> Mg(OH)2

Question 19

Reaction of Al2O3 and SiO2 with water

Answer 19

Both DO NOT react

Question 20

Reaction of Phosphorus oxide and water

Answer 20

P4O10(s) + 6H2O(l) —-> 4H3PO4(aq)

Question 21

Reaction of suflur dioxide and sulfur trioxide with water

Answer 21

SO2(g) + H2O —-> H2SO3(aq)
SO3(s) + H2O —-> H2SO4(aq)

Question 22

Show the 3 stages of dissociation of H3PO4 (weak acid)

Answer 22

H3PO4 —-> H+ H2PO4-
H2PO4- —-> H+ + HPO4 2-
HPO4 2- —-> H+ + PO3 3-

Question 23

Show the full dissociation of H2SO4

Answer 23

H2SO4 —-> H+ + HSO4-
HSO4- ⇌ H+ + SO4 2-

Question 24

What is colours do SO2 and SO3 produce when mixed with a universal indicator

Answer 24

SO2(aq) orange-red
SO3(aq) red

Question 25

Reaction of Sodium oxide with acids HCl H2SO4 2H3PO4

Answer 25

Na2O(s) + 2HCl(aq) → 2NaCl(aq) + H20(l) Na2O(s) + H2SO4(aq) → Na2SOa(aq) + H20(l) 3Na2O(s) + 2H3PO4(aq) →2NaзРO4(aq) + 3H2O(l)

Question 26

Reaction of magnesium oxide with acids HCl H2SO4 2H3PO4

Answer 26

MgO(s) + 2HCl(aq) → MgCl(aq) + H2O(l) MgO(s) + H2SO4(aq) → MgSO4(aq) + H2O(l) 3MgO(s) + 2H3PO4(aq) → (Mg)4(PO4)2(aq) + 3Н2O(l)

Question 27

Reaction of aluminium oxide with acid HCl

Answer 27

Al2O3(s) + 6HCl(aq) → 2AICl3(aq) + 3H2O(l)

Question 28

Reaction of sodium oxide with acid HCl

Answer 28

NaOH(aq) + HCl(aq) → NaCl(aq) + H2O(l)

Question 29

Reaction of magnesium oxide with acid HCl

Answer 29

Mg(OH)2(s) + 2HCl(aq) → MgCl2(aq) + 2H2O(l)

Question 30

Reaction of Aluminium oxide with base NaOH

Answer 30

Al2O3(s) + 2NaOH(aq) + 3H2O(l) → 2NaAI(OH)4(aq) water is a reactant NOT a product

Question 31

Reaction of Silicion oxide with bases 2NaOH Mg(OH)2 Ca(OH)2

Answer 31

SiO2(s) + 2NaOH(aq) → NazSiO3(aq) + H2O(l) SiO2(s) + Mg(OH)2(aq) → MgSiO3(aq) + H2O(l) SiO2(s) + Ca(OH)2(aq) → CaSiO3(aq) + H2O(l)

Question 32

Reaction of phosphorus oxide with bases 12NaOH Mg(OH)2

Answer 32

P4O10(l) + 12NaOH(aq) → 4Na3PO4(aq) + 6H2O(l) P4O10(s) + 6Са(ОН)2(aq) → 2Cа3(РО4)2(aq) + 6H2О(l)

Question 33

Reaction of Sulfur dioxide with bases NaOH

Answer 33

SO2(g) + 2NaOH(aq) → Na2SO3(aq) + H2O(l)

Question 34

Reaction of Sulfur trioxide with bases NaOH

Answer 34

SO3(s) + 2NaOH —-> Na2SO4(aq) + H2O(l)

Question 35

Neutralisations in the absence of water reactions of Na2O and MgO with phosphorus oxide

Answer 35

6Na2O(s) + P4O10(s) → 4Na3PO4(s) 6MgO(s) + P4010(s) →2Mg3(PO4)2(s)