22 Periodicity

Question 1

Na mp and structure

Answer 1

98*C, giant metallic

Question 2

Na reaction with water + observations

Answer 2

2Na + 2H2O —> 2NaOH + H2
- fizzing, floats (denser than H2O)
- flame = orange

Question 3

Na reaction with oxygen + observations

Answer 3

4Na + O2 —–> 2Na2O
- highly reactive
- flame = orange

Question 4

Mg mp and structure

Answer 4

650*C, giant metallic

Question 5

Mg reaction with water + observations

Answer 5

Mg + 2H2O —-> Mg(OH)2 + H2
( steam = Mg + H20 –> MgO + H2)
- very slow bubbling
- flame = white (steam)

Question 6

Mg reaction with oxygen + observations

Answer 6

2Mg + O2 —-> 2MgO
- flame = bright white
- white powder formed

Question 7

Al mp and structure

Answer 7

660*C, giant metallic

Question 8

Al reaction with oxygen + observations

Answer 8

4Al + 3O2 —-> 2Al2O3
- flame = bright white
- white powder formed

Question 9

Si mp and structure

Answer 9

1414*C, giant covalent

Question 10

Si reaction with oxygen + observations

Answer 10

Si + O2 —-> SiO2
- flame = bright white
- grey/white powder formed

Question 11

P4 mp and structure

Answer 11

44*C, simple covalent

Question 12

P4 reaction with oxygen + observations

Answer 12

P4 + 5O2 —-> P4O10
- flame = bright blue
- (choking gas)

Question 13

Cl2 mp and structure

Answer 13

-102*C, simple covalent

Question 14

Cl2 reaction with water + observations

Answer 14

Cl2 + H2O <====> HCl + HOCl
- dissolves to give light green solution

Question 15

Na2O mp and structure

Answer 15

1275*C (solid), ionic

Question 16

Na2O reaction with water + what happens

Answer 16

O2- + H2O → 2 OH-
Na2O + H2O → 2 NaOH(aq)
- The Na+ and O2- ions
dissolves in water and then
the O2- ions react with
water
- pH 14

Question 17

Na2O reaction with acids + nature of oxide

Answer 17

Na2O + 2 H+ → 2 Na+ + H2O
BASIC

Question 18

MgO mp and structure

Answer 18

2900*C (soild)
Ionic - higher mp due to smaller ion and larger charge, smaller atomic radius

Question 19

MgO reaction with water + what happens

Answer 19

O2- + H2O → 2 OH-
MgO + H2O → Mg(OH)2(aq)
- slightly soluble
- Some Mg2+ and O2- ions
dissolve in water, O2- ions react with
water
- pH 10

Question 20

MgO reaction with acids + nature of oxide

Answer 20

MgO + 2 H+ → Mg2+ + H2O
BASIC

Question 21

Al2O3 mp and structure

Answer 21

2040*C (solid)
ionic - exhibits covalent character

Question 22

Al2O3 reaction with water

Answer 22

no reaction,
INSOLUBLE - very high lattice enthalpy

Question 23

Al2O3 reaction with acids/alkalis + nature of oxide

Answer 23

ACIDS - Al2O3 + 6H+ → 2Al3++ 3H2O
ALKALI - Al2O3 + 2OH- + 3H2O → 2 Al(OH)4-
AMPHOTERIC

Question 24

SiO2 mp and structure

Answer 24

1610*C (solid), giant covalent

Question 25

SiO2 reaction with water

Answer 25

no reaction,
INSOLUBLE - lattice of very strong covalent bonds

Question 26

SiO2 reaction with alkali + nature of oxide

Answer 26

SiO2 + 2OH- → SiO32- + H2O
ACIDIC

Question 27

P4O10 mp and structure

Answer 27

580*C (solid), molecular

Question 28

P4O10 reaction with water + what happens

Answer 28

P4O10 + 6H2O → 4H3PO4
- reacts violently
- H2O molecules attach the
d+ P atoms, leading to the
release of H+ ions

Question 29

P4O10 reaction with alkalis + nature of oxide

Answer 29

P4O10 + 12OH- → 4PO43- + 6 H2O
ACIDIC

Question 30

SO2 mp and structure

Answer 30

-75*C (gas) , molecular

Question 31

SO2 reaction with water + what happens

Answer 31

SO2 + H2O → H2SO3
- Dissolves
- H2O molecules attach the
d+ S atoms, leading to the
release of H+ ions

Question 32

SO2 reaction with alkalis + nature of oxide

Answer 32

SO2 + 2OH- → SO32- + H2O
ACIDIC

Question 33

SO3 mp and stucture

Answer 33

17*C (liquid?), molecular

Question 34

SO3 reaction with water + what happens

Answer 34

SO3 + H2O → H2SO4
- reacts violently
- H2O molecules attach the
δ+ S atoms, leading to the
release of H+
- pH 0

Question 35

SO3 reaction with alkalis + nature of oxide

Answer 35

SO3 + 2OH- → SO42- + H2O
ACIDIC