1. Elements in group 1 & 2
Inorganic chemistry

2. Define ionisation energy
STARTER
Define ionisation energy
What is the trend for ionisation energy as we go down the group?
Explain this trend.

3. Answers
Energy required to remove an electron from a gaseous atom or ion
As you move down a group, ionization energy decreases.
More shielding, electrons are further from the nucleus and thus easier to remove the outermost one.

4. LO; Investigating group 2 metals
Success criteria
Understand the chemical properties of group 2 metals (LD)
Explain the reaction between water and group 2 metals using equations (MD)
Explain the trend of reactivity when group 2 elements react with oxygen or water (HD)

5. Group 2
Chemical Properties
Physical Properties
Solubility

6. Group 2 elements Group 2 Be
Group 2 elements can react with water, oxygen & chlorine. When group 2 elements react they form ions with 2+ charges. This is because they lose the two electrons on their outer shell.
You will need to know how to write the equations for all these reactions.
Group 2 Be Mg Ca Sr Ba

7. Challenge; use state symbols
Write me and equation for any group 2 metal with water?
What do you think the products are?
Challenge; use state symbols

8. Sr(s) + 2H2O(l) → Sr(OH)2(aq) + H2(g)
Reaction with water
When group 2 metals react with water they form a Metal hydroxide & Hydrogen
oxidation states
Sr(s) + 2H2O(l) → Sr(OH)2(aq) + H2(g) +1 +2
Sr is Oxidized – The Ox state goes from 0 to +2 – Loses Electrons
Hydrogen is Reduced – The Ox state goes from +1 to 0 – Gains Electrons

9. Reaction with Water Be Doesn’t react Mg Reacts very slowly Ca SteadilySr
Fairly Quickly Ba
Rapidly
Reactivity increases as we go down the group

10. Explain the trend in reactivity
The reactivity for the group 2 metals increases as we go DOWN the group
Because it is easier to remove the electrons for 2+ charge
Shielding increases as we go down the group
Less nuclear attraction between the outer electrons and the nucleus

11. FLAME TESTs

12. Flame Tests Li Red Na Orange/Yellow K Lilac Ca Brick-red Rb Sr Crimson
When group 1 or group 2 metals are burned in oxygen, coloured flames are produced. Li
Red Na
Orange/Yellow K
Lilac Ca
Brick-red Rb Sr
Crimson Cs
Blue Ba
Green

13. Reaction with oxygen
When group 2 metals react with oxygen, you get a solid white oxide
2Mg(s) + O2(g) ® 2MgO(s)
oxidation states +2 -2
Mg is Oxidized – The Ox state goes from 0 to +2 – Loses Electrons
Oxygen is Reduced – The Ox state goes from 0 to -2 – Gains Electrons

14. Reaction with CHLORINE
When group 2 metals react with chlorine, they form metal chloride
Ca(s) + Cl2(g) ® CaCl2(s)
oxidation states +2 -1
Ca is Oxidized – The Ox state goes from 0 to +2 – Loses Electrons
Chlorine is Oxidized – The Ox state goes from 0 to -1 – Loses Electrons

15. Plenary Which is the least reactive metal in Group 2?
Why does reactivity with water increase down Group 2?
Barium can be burned in chlorine gas. Write an equation for the reaction, including state symbols.
Plenary