Topic 4: Inorganic Chemistry (Group 2)

Question 1

The trend in ionisation energy down group 2. Explain the factors

Answer 1

Down the group:
+Nuclear charge increases
+So ionisation energy increases (more attraction between the nucleus and electrons)

• But Down the group, more quantum shells are added increasing the energy for the outermost electron (less energy to remove)
• This also increases the repulsion force felt by the outermost electron

-+ OVERALL the combined effect of the two factors outweighs the effect of the first factor
Therefore ionisation energy down the group decreases

+Nuclear charge increases down the group so the force of attraction for the electron being removed increases, therefore, an increase in ionisation energy as the outer electron has less energy

• However, as each quantum shell is added the energy of the outermost electron increases
• The repulsion force on the outermost electron increases
• Overall the combined effect of the two factors outweighs the effect of the first factor
• Decreasing ionisation energy down the group

Question 2

The trend in reactivity down Group 2

Answer 2

Increase in reactivity as it is easier to remove the two outermost electrons

Question 3

Group 2 metals Reaction with Oxygen

Answer 3

2M(s) + O2(g) ➝ 2MO(s)

Question 4

Reaction with chlorine

Answer 4

M(s) + Cl2(g) ➝ MCl2(s)

Question 5

Group 2 Metals Reaction with Water (more vigorous down the group) Equation

Answer 5

M(s) + 2H2O(l) ➝ M(OH)2(aq) + H2(g)

Question 6

Calcium + water observation

Answer 6

Forms a solid white precipitate of Ca(OH)2 which is insoluble and H2 gas
-therefore Ca(OH)2 is not aqueous it is solid

Question 7

Magnesium + steam

Answer 7

Mg(s) + H2O(g) ➝ MgO(s) + H2(g)

-Forms magnisium oxide

Question 8

Reactions of oxides with water

Answer 8

MO(s) + H2O(l) ➝ M(OH)2 (aq)
-FORMS A METAL HYDROXIDE
Simplified(as there is no change to M2+):
O2- + H2O ➝ 2OH-

Question 9

Trends in solubility of hydroxides (Group 2)

Answer 9

solubility increases down the group

Question 10

Group 2 Reaction with oxides and hydroxides with acids

Answer 10

CaO + 2HNO3 ➝ Ca(NO3)2 + H2O

Question 11

Basic oxides definition

Answer 11

They are oxides of metals that react with water to form hydroxides and with acids to form salts and water

Question 12

The trend in solubility of Sulfates down a group

Answer 12

Solubility decreases (Low solubility of Barium sulfate is used to test for sulfate ions)

Question 13

What is Thermal Stability?

Answer 13

The measure of the extent to which a compound decomposes when heated

Question 14

What are the two types of decomposition? (for metal nitrates)

Answer 14

Lesser(O2) and greater (Brown fumes NO2)

Question 15

What is the trend in thermal stability down both groups?

Answer 15

Increases as there is a decrease in the polarising ability

Question 16

Lesser decomposition for nitrates

Answer 16

metal nitrate(NO3) ➝ metal nitrite (MNO2) + oxygen

Question 17

Greater decomposition (nitrates)

Answer 17

metal nitrate ➝ metal oxide + nitrogen dioxide + Oxygen

4 LiNO3 → 2 Li2O + 4 NO2 + O2

2 Ca(NO3)2 → 2 CaO + 4 NO2 + O2

Question 18

What compounds can decompose greater?

Answer 18

Li,Be,Mg,Ca,Sr,Ba(Nitrate/Carbonate)

All group 2 metals and Li

Question 19

Two types of decomposition for carbonates

Answer 19

• No decomposition

- Decomposition

Question 20

Decomposition of Metal carbonates

Answer 20

Metal carbonate ➝ metal oxide + carbon dioxide

Question 21

What metal carbonates decompose

Answer 21

Li,Be,Mg,Ca,Sr,Ba

Question 22

What is meant by the term Polarising power?

Answer 22

the ability of a cation to distort the electron cloud around an anion

Question 23

Factors affecting the polarising ability

Answer 23

• Ionic radius

- Charge of cation