1. Access to Science – Chemistry - periodicity
Prepare for learning: pens, notebooks bags and stuff to side benches

2. Learning aims for the session:
Reflective Learner
Effective Participator
Team worker
Learning aims for the session:
Describe the variation of atomic radius, first ionisation energy and electronegativity of group 1 elements.
Describe the reactions of group 1 elements with oxygen, chlorine and water.
Carry out qualitative analysis of common cations and anions.
Liteion racy and Numeracy
News!

3. Physical data for Group I elements
Atomic radius /nm
1st Ionisation energy/kJ mol-1
Melting point/ºC
Lithium
Sodium
Potassium
Rubidium
Caesium
0.123
519
180
0.157
494 98
0.203
418 64
0.216
402 40
0.235
376 29

4. Changes down Group 1 increases
Atomic radius
increases
because of the increasing number of energy levels
1st Ionisation energy
decreases
because of increasing size and shielding
Melting point
Because of increasing size between adjacent atoms and increased nuclear shielding resulting in longer, weaker metallic bonds.
decreases

5. Group 1 elements
They are typical metals – forming largely ionic compounds with other elements
They release electrons to form positive ions
Na  Na e-
So, will form ionic bonds with other elements such as oxygen, water and chlorine for example.
They are reducing agents
i.e. They donate electrons to oxidising agents

6. OILRIG They release electrons to form positive ions Na  Na+ + e-
They are reducing agents
i.e. They donate electrons to oxidising agents
Oxidation Is Loss; Reduction Is Gain
When a substance is oxidised it loses electrons, so becomes more positively charged
The substance that is oxidised is known as a reducing agent because in the process of being oxidised / losing electrons it causes reduction or the giving electrons to another substance.
When substance is reduced it gains electrons, so becomes more negatively charged
The substance that is reduced is known as an oxidising agent because in the process of being reduced / gaining electrons it is causing oxidation or taking electrons from another substance.
4Na + O Na2O
Here sodium has lost it’s outer electron to oxygen, so is oxidised.
Sodium is acting as a reducing agent because it is giving its electrons to oxygen.
Oxygen can be defined as being reduced in the process because it has gained electrons.
Oxygen can also be described as an oxidising agent as it has caused reduction / loss of electrons from sodium in the process.

7. Reactivity of group 1 elements
Reactivity increases down the Group because…
the outer electron becomes easier to remove as the atomic size increases and the nuclear shielding increases.

8. Reactivity of group 1 Demo http://www.youtube.com/watch?v=m55kgyApYrY
Individuals - Describe what you witnessed for the reactivity of the group 1 metals during the demo and video.
Pair – describe to a partner
Share - describe to the group.
Make your notes

9. Reaction with water 2Li(s) + 2H2O(l)  2LiOH(aq) + H2(g)
lithium hydroxide
2Na(s) + 2H2O(l)  2NaOH(aq) + H2(g)
sodium hydroxide
2K(s) + 2H2O(l)  2KOH(aq) + H2(g)
potassium hydroxide
2Rb(s) + 2H2O(l)  2RbOH(aq) + H2(g)
rubidium hydroxide
2Cs(s) + 2H2O(l)  2CsOH(aq) + H2(g)
caesium hydroxide
click for sodium + acid

10. Solubility in organic solvents
Solubility of the halides – salts of group 17 (fluorides, chlorides, bromides and iodides)
Solubility in water
Solubility in organic solvents
Lithium halides
Other Group 1 halides
slightly soluble
slightly soluble
very soluble
insoluble
Lithium salts are anomalous because of the small size of the cation, they tend to draw anions closer leading to more covalent properties present in the salts.

11. Thermal decomposition of nitrates
2LiNO2  Li2O NO ½O2
lithium nitrate
lithium oxide
nitrogen dioxide
2NaNO3  2NaNO O2
sodium nitrate
sodium nitrite
The anomalous character of lithium nitrite is due to its covalent character, it’s more like group 2 carbonates, that also decompose this way on heating.

12. Summary LiNO3  LiNO2 + Li2O NaNO3  NaNO2 KNO3  KNO2 RbNO3  RbNO2
CsNO3 
CsNO2

13. Carbonates Thermal decomposition of lithium carbonate
2LiCO3  Li2O CO2
Again, the anomalous character of lithium carbonate is due to its covalent character, it’s more like group 2 carbonates, that also decompose on heating.

14. Summary The Group 1 metals are reactive and form ionic salts.
Compounds are generally soluble in water, insoluble in organic solvents and are thermally stable.
Lithium compounds exhibit anomalous properties.

15. http://aschool.us/random/random-pair.php Siobhan Naomi Leyton Kevin
Sean
Andrew
Nicola
Laura
Hannah
Rebekha
Jacob
Anthony
Maria
Joe
Gemma
Sarah
Glen
Amanda
Abigail
Hasib
Eamon
Stephen
Inna

16. Qualitative analysis of salts
What’s in a salt?
An anion and a cation e.g. Na+ Cl-
We have looked at a way of finding out what metal cation is present – flame tests
However, this doesn’t work for all cations – some do not give coloured flames, or give similar colours so it is difficult to distinguish between them.
We are now going to look at some other ways of telling what is in a substance.

17. Tests can be grouped
For cations: often we can distinguish between metal cations by adding a alkali such as sodium hydroxide or ammonium hydroxide (ammonia in solution).
For anions: we can test for carbonates, sulphates, nitrates and halides by using simple tests too.
demo

18. Read first! Pairs!
There are lots of tests to analyse compound to identify what is present, here are a few of them
Work slowly through the analysis and record what you find…
You will do this again in a few weeks with some unknowns as part of your assignment, so make clear notes of results and you might want to take photographs too.

19. Results

20. Periodic Table
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