A-LEVEL CHEMISTRY: 3.2.4: Periodicity of Period 3 (SaveMyExams)

Question 1

Magnesium reacts very ___ with cold water to form the ___, but reacts more ___ with ___ to form the ___.

Answer 1

slowly, hydroxide, quickly, steam, oxide

Question 2

all Period 3 Elements react with oxygen to form…

Answer 2

oxides

Question 3

Sodium burns with a ___ flame when it reacts with Oxygen to produce a ___ solid.

Answer 3

yellow, white

Question 4

explain the reaction between sodium and oxygen: (2)

Answer 4

-Na burns with yellow flame

-produces white solid

Question 5

explain the reaction between Magnesium and Oxygen: (2)

Answer 5

-Mg burns with white flame

-produces white solid & smoke

Question 6

explain the reaction between Aluminium and Oxygen: (2)

Answer 6

-Al burns with white flame

-produces white solid & smoke

Question 7

explain the reaction between Silicon and Oxygen: (2)

Answer 7

-Si burns with white flame

-produces white solid & smoke

Question 8

explain the reaction between Sulfur and Oxygen: (2)

Answer 8

-S burns with blue flame

-produces acidic choking gas

Question 9

equation for reaction between Sodium & Oxygen:

Answer 9

4Na (s) + O2 (g) —–> 2Na2O (s)

Question 10

equation for reaction between Magnesium & Oxygen:

Answer 10

2Mg (s) + O2 —–> 2MgO (s)

Question 11

equation for reaction between Aluminium & Oxygen:

Answer 11

4Al (s) + 3O2 (g) —–> 2Al2O3 (s)

Question 12

equation for reaction between Silicon & Oxygen:

Answer 12

Si (s) + O2 (g) —–> SiO2 (s)

Question 13

equation for reaction between Phosphorus & Oxygen:

Answer 13

4P (s) + 5O2 (g) —–> P4O10 (s)

Question 14

equation for reaction between Sulfur & Oxygen:

Answer 14

S (s) + O2 (g) —–> SO2 (g)

Question 15

explain the reaction between Phosphorus and Oxygen: (2)

Answer 15

-P burns with white flame

-produces white solid & smoke

Question 16

Sodium is stored in ___, & Phosphorus is stored in ___. why?

Answer 16

paraffin oil, water

to prevent them from reacting with Oxygen

Question 17

the Metal Oxides (Na2O, MgO, Al2O3) are ___.

Answer 17

Ionic

Question 18

explain why ionic metal oxides have ___ melting points: (2)

Answer 18

high

-giant ionic lattice structures

-strong electrostatic forces of attraction between between +ve & -ve ions

Question 19

why are Metal Oxides ionic?

Answer 19

due to high electronegativity difference between +ve Metal ions & -ve oxygen ions

Question 20

explain the trend in the melting points of ionic oxides across period 3:

Answer 20

-increases

-increasing atomic number
-increasing nuclear charge

-increased charge on the cation
-stronger electrostatic forces of attraction

Question 21

how to prove that compounds contain ions:

Answer 21

Melt the solids & test of they Conduct electricity

Question 22

SiO2 is ___.

Answer 22

macromolecular

Question 23

SiO2 is ___. explain the mp & bp:

Answer 23

Macromolecular

v. high mp & bp because:
-many v. strong covalent bonds between atoms

-high energy needed to break the many strong covalent bonds

-∴ v. high mp & bp

Question 24

P4O10 (s) and SO2 (g) are ___ ___. explain their properties. (3)

Answer 24

simple molecular

-weak intermolecular forces (van der waals + permanent dipoles)

-low mp’s

-covalent because of small electronegativity difference between Non-Metal & O atoms

Question 25

Metal ionic oxides tend to react with water to form ___ which are ___.

Answer 25

hydroxides, alkaline

Question 26

Na2O (s) + H2O (l) -----> ...

Answer 26

2Na+ (aq) + 2OH- (aq) pH 13 (this is a vigorous exothermic reaction)

Question 27

Al2O3 and SiO2 ___ ___ ___ in water. why?

Answer 27

do not dissolve because of the high strength of the Al2O3 ionic lattice & the SiO2 macromolecular structure, so they give a neutral pH 7

Question 28

MgO is better than NaOH for treating acid in rivers & stomach. why?

Answer 28

because it is only sparingly soluble & weakly alkaline, so using an excess would not make the water excessively alkaline

Question 29

The non-metal, simple molecular, covalent, oxides react with water to give...

Answer 29

acids

Question 30

vigorous exothermic reaction between P4O10 & H2O: pH:

Answer 30

P4O10 (s) + 6 H2O (l) -----> 4 H3PO4 (aq) pH: 0

Question 31

the trend when oxides react with water is that ionic metal oxides show ___ behaviour, whereas the non-metal covalent oxides show ___ behaviour.

Answer 31

basic, acidic

Question 32

ionic metal oxides react with acids to make salts:

Answer 32

acid + base -----> salt + water

Question 33

Amphoteric oxides:

Answer 33

Aluminium oxide can act as both an acid and an alkali and is therefore called amphoteric

Question 34

SiO2 has a ___ ___ ___ with ___ ___ ___. what does this stop?

Answer 34

giant covalent structure, very strong bonds this stop SiO2 dissolving or reacting with water and weak alkali solutions. it will, however, react with very concentrated NaOH

Question 35

what will SiO2 still react with?

Answer 35

very concentrated NaOH

Question 36

why doesn't SiO2 dissolve or react with water or weak alkali solutions? (2)

Answer 36

because: -giant covalent structure -very strong bonds