Group 2 Elements

1. Chemical Formula for Limewater

1.1. Ca(OH)2 (aq)

2. Describe & Explain Trend of Solubility of Hydroxides from Mg to Ba

2.1. Increase in hydration enthalpy but decrease in LD enthalpy

2.2. LD enthalpy outweighs hydration

2.3. Solubility increase

3. Describe & Explain Trend in Reactivity From Mg to Ba

3.1. First ionisation energy decreases

3.2. Less energy required to remove outermost electron

3.3. Metal can be readily & more easily oxidised

3.4. Reactivity increases

4. Explain Why Atomic Radius Increases From Mg to Ba

4.1. Electron shielding increases

4.2. Outermost electrons further away from nucleus

4.3. Atomic radius increases down a group

5. Reaction of Mg with Water Stops After Very Short Time

5.1. Reaction with water forms Mg(OH)2

5.2. Mg(OH)2 insoluble in water so forms a barrier

5.3. No more water in contact with Mg so reaction stops

6. Describe Trend in Melting Point From Mg To Ba

6.1. Generally decreases from Mg to Ba

6.2. Mg = An exception; has lowest MP of all group 2 metals

7. Test for Sulphate Ions

7.1. Add BaCl to substance

7.2. Milky white precipitate formed

8. Explain Why Test for Sulphate Ions Must be in Acidic Conditions

8.1. Other negative ions from white precipitates in BaCl

8.2. SO4 precipitates are insoluble in acidic conditions; others are not

9. Describe & Explain Trend in Solubility of Sulphates from Mg to Ba

9.1. Decrease in hydration enthalpy but not much change in LD enthalpy

9.2. Solubility decreases

10. Milk of Magnesia

10.1. Form of Magnesium Hydroxide

10.2. Used as medicine for constipation

11. Explain Why Melting Point Decreases from Mg to Ba

11.1. Atomic radius increases down group

11.2. Outermost electrons are further away from nucleus

11.3. Strength of metallic bond decreases, so less energy needed to break them, hence lower MP

12. Slaked Lime

12.1. Solid form of Ca(OH)2

12.2. Used to clean drinking water & neutralise acidic soils

13. Explain Why Barium Meal Isn't Toxic But Barium Is

13.1. Contains form of Barium Sulphate

13.2. BaSO4 is insoluble, so does not enter blood stream

14. Origin of Name of 'Milk of Magnesia'

14.1. It contains magnesium and looks like and has the texture of milk.

15. General Equation of Group 2 Metal and Water

15.1. M(s) + 2H2O(l) --> M(OH)2(aq) + H2

16. Equation for Reaction of Mg With Steam

16.1. Mg(s) + 2H2O(g) --> MgO(s) + H2(g)

17. Describe Trend in Atomic Radius from Mg to Ba

17.1. Increases down any group

17.2. Increases from Mg to Ba

18. Describe Trend in Ionisation Energy

18.1. Decreases down any group

18.2. Decreases from Mg to Ba

19. Electronic Configuration

19.1. Beryllium (Be) - [He] 2s2

19.2. Magnesium (Mg) - [Ne] 3s2

19.3. Calcium (Ca) - [Ar] 4s2

19.4. Strontium (Sr) - [Kr] 5s2

19.5. Barium (Ba) - [Xe] 6s2

20. Use of Barium Meal

20.1. Is a liquid that deflects X-rays

20.2. Drunk before x-ray to observe intestinal obstructions

21. Explain Trend in 1st Ionisation Energy From Mg to Ba

21.1. Increase in electron shielding (and hence atomic radius) & nuclear charge

21.2. Ionisation energy generally increases down a group