inorganic 2- period 3 oxides

Question 1

why does magnesium have a higher mp than sodium

Answer 1

forms a 2+ charge so delocalised electrons have a stronger attraction to positive charge

Question 2

reaction of sodium with water

Answer 2

2Na +H2O -> 2NaOH +H2

Question 3

observations of sodium with water

Answer 3

fizzes, vigorous, pH 13-14

Question 4

reaction of magnesium with WATER

Answer 4

Mg + 2H2O(l) -> Mg(OH)2 +H2

Question 5

observations of magnesium with water

Answer 5

slow, few bubbles, pH 10

Question 6

reaction of magnesium with STEAM

Answer 6

Mg + H2O(g) -> MgO +H2

Question 7

observations of magnesium with steam

Answer 7

faster, bright white flame

Question 8

reaction of sodium with oxygen

Answer 8

4Na(s) + O2(g) -> 2Na2O(s)

Question 9

reaction of magnesium with oxygen

Answer 9

2Mg(s) +O2(g) -> 2MgO(s)

Question 10

reaction of aluminium with oxygen

Answer 10

4Al + 3O2 -> 2Al2O3(s)

Question 11

reaction of silicon with oxygen

Answer 11

Si(s) + O2(g) -> SiO2 (s)

Question 12

reaction of phosphorus and oxygen

Answer 12

P4(s) + 5O2(g) -> P4O10 (s)

Question 13

reaction of sulphur with oxygen (dioxide)

Answer 13

S(s) + O2(g) -> SO2 (s) (+4 CHARGE)

Question 14

what do you need to form sulphur trioxide

Answer 14

high temperature and catalyst

Question 15

reaction of sulphur with oxygen (trioxide)

Answer 15

2SO2(s) + O2(g) -> 2SO3 (s) (+6 CHARGE)

Question 16

trends in reactions

Answer 16

Na: vigorous, yellow flame white solid
Mg :vigorous, white flame + solid
Al and Si : slow, white flame
P:combusts, white flame + solid
S: gently, blue flame

Question 17

explain properties of sodium, magnesium and aluminium oxides

Answer 17

ionic oxides. giant lattice strutures, SEFABOCI so higher melting points.

Question 18

why is Mg melting point higher than Al

Answer 18

Mg has a 2+ charge so attracts O2- ions stronger

Question 19

why is aluminuim oxide an anomaly

Answer 19

it is ionic but shows covalent character because its high charge distorts the electron cloud of the oxide ion

Question 20

explain properties of silicon dioxide

Answer 20

giant covalent (macromolecular). many strong covalent bonds which require a lot of energy to break so high mp and bp

Question 21

explain the properties of phosphorus oxide and sulphur dioxide

Answer 21

simple covalent. weak IMF (VWD and dipoles) so have lower mps. phosphorus oxide is a bigger molecule and has more e- so has a higher mp.

Question 22

why are ionic oxides ionic

Answer 22

large difference in electronegativity between metal and O

Question 23

why are covalent oxides covalent

Answer 23

small difference in electronegativity between non-metal and O atoms

Question 24

what do the basic oxides form with water

Answer 24

alkaline solutions

Question 25

reaction of Na2O and water

Answer 25

Na2O+H2O-> 2NaOH pH 14

Question 26

reaction of MgO and water

Answer 26

MgO (s) + H2O (l) → Mg(OH)2 (aq) Ph 10

Question 27

what do simple covalent oxides form

Answer 27

acidic solutions

Question 28

reaction of phosphorus oxide and water

Answer 28

P4O10 (s) + 6H2O (l) → 4H3PO4 (aq) PH 2