Group 2, the alkaline earth metals

Question 1

Describe the atomic radius in Group 2

Answer 1

Increases down the group - more electron shells added

Question 2

Describe the trend in ionisation energy in Group 2

Answer 2

• decreases down the group
• increase in atomic radius and shielding
• easer to remove due to weaker attraction

Question 3

Describe the trend in electronegativity in Group 2

Answer 3

• decreases down the group
• metal atoms get bigger
• bonding pair further away from nucleus

Question 4

Describe the trend of melting points in Group 2

Answer 4

• decreases down the group
• outer electrons further from nucleus = shielding
• electrostatic attraction with delocalised electrons and +ions
• less energy to overcome attraction

Question 5

Describe the visual observations of Grp 2 and water reacting

Answer 5

Be - no reaction 
Mg - vigorous w/ steam 
Ca - reacts moderately + Hydroxide 
Sr - rapidly, Hydroxide 
Ba - Vigorously + Hydroxide

Question 6

What is the general equation for Grp2 reactions with water?

Answer 6

M (s) + 2H2O (l) → M(OH)2 (s) + H2 (g)

Question 7

What is the formula of Mg reacting with steam?

Answer 7

Mg (s) + H2O (g) → MgO (s) + H2 (g)

Question 8

Describe the trend of reactivity in Grp 2

Answer 8

easier to remove outer electron

Question 9

Describe the solubility of hydroxides in Grp 2

Answer 9

• Increases as you go down the group

PH increases

Question 10

Describe the solubility of sulphates in Grp 2

Answer 10

• Decreases down the group

Question 11

What is Mg(OH)2 in terms of solubitly?

Answer 11

Sparingly soluble

Question 12

What is the use of Ca(OH)2?

Answer 12

Agriculture

- Slakked lime that works to neutralise acidic soil

Question 13

How is Mg(OH)2 used in medicine ?

Answer 13

• can be used as antiacids

- indigestion tablets (swallow due to insolubility)

Question 14

How can BaSO4 be used in medicine?

Answer 14

• Absorbs X-ray (radiocontrast)
• known as “Barium Meal”
• safe as it is insoluble so not absorbed by the body

Question 15

What is the test for sulphate ions?

Answer 15

• Add HCL
• Then add BaCl2
• Positive result = white p.p of Barium Sulphate

Question 16

Why do we add HCL in the test for sulphate ions?

Answer 16

Removes unwanted ions (carbonate or sulfate) being made - cause they can give a white p.p

Question 17

What is the general equation for Group 2 reacting with H2SO4?

Answer 17

M(s) + H2SO4(aq) —-> MSO4(aq) + H2

Question 18

What is the is general equation with Group 2 with HCL?

Answer 18

M + HCL(aq) —-> MCL2(aq) + H2

Question 19

What is the general reaction of grp 2 with Oxygen?

Answer 19

2M+O2 —–> 2MO

Question 20

Describe the observations when Grp 2 react with H2SO4?

Answer 20

Be - Vigorously 
Mg - Vigorously 
Ca - Slowed down by sulphate layer 
Sr - Quickly stopped insoluble layer 
Ba - Quickly stopped insoluble layer

Question 21

How is Mg used in the extraction of titanium?

Answer 21

• Mg reduced in 100C

- TiCl4(g) + 2Mg(l) —–> Ti(s) + 2MgCl2(l)

Question 22

How are CaO (lime) + CaCO3 (limestone) to remove SO2 from flue gas?

Answer 22

• Slurry made by mixing with either and H2O
• Then sprayed on flue gases
• SO2 reacts with alkaline surry
• produces Solid waste = CALCIUM SULFIDE