Group 2 Elements

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

1.1. First ionisation energy decreases

1.2. Less energy required to remove outermost electron

1.3. Metal can be readily & more easily oxidised

1.4. Reactivity increases

2. Explain Why Atomic Radius Increases From Mg to Ba

2.1. Electron shielding increases

2.2. Outermost electrons further away from nucleus

2.3. Atomic radius increases down a group

3. Electronic Configuration

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

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

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

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

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

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

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

4.2. Solubility decreases

5. Chemical Formula for Limewater

5.1. Ca(OH)2 (aq)

6. Describe Trend in Ionisation Energy

6.1. Decreases down any group

6.2. Decreases from Mg to Ba

7. Describe Trend in Atomic Radius from Mg to Ba

7.1. Increases down any group

7.2. Increases from Mg to Ba

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

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

8.2. Ionisation energy generally increases down a group

9. Use of Barium Meal

9.1. Is a liquid that deflects X-rays

9.2. Drunk before x-ray to observe intestinal obstructions

10. Equation for Reaction of Mg With Steam

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

11. General Equation of Group 2 Metal and Water

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

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

12.1. Reaction with water forms Mg(OH)2

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

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

13. Describe Trend in Melting Point From Mg To Ba

13.1. Generally decreases from Mg to Ba

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

14. Test for Sulphate Ions

14.1. Add BaCl to substance

14.2. Milky white precipitate formed

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

15.1. Other negative ions from white precipitates in BaCl

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

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

16.1. Increase in hydration enthalpy but decrease in LD enthalpy

16.2. LD enthalpy outweighs hydration

16.3. Solubility increase

17. Milk of Magnesia

17.1. Form of Magnesium Hydroxide

17.2. Used as medicine for constipation

18. Explain Why Melting Point Decreases from Mg to Ba

18.1. Atomic radius increases down group

18.2. Outermost electrons are further away from nucleus

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

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

19.1. Contains form of Barium Sulphate

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

20. Slaked Lime

20.1. Solid form of Ca(OH)2

20.2. Used to clean drinking water & neutralise acidic soils

21. Origin of Name of 'Milk of Magnesia'

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