AlkaliMetals

OC48 describe the general properties of the alkali metals and understand that alkali metals are in Group I of the Periodic Table and have similar properties

Group 1 metals in the periodic table are known as Alkali metals.

Examples,

Na, Sodium, K Potassium, Li Lithium,

Like all metals,

  • they react with oxygen
  • they are shiny
  • they are solid at room temperature.
  • they conduct heat and electricity.
  • they corrode in air

But they are also different,

    • they are so reactive with water that they cannot be left in the air
    • they are also quite soft and easily cut with a knife.

Title

OC49 describe the reactions of the alkali metals with air and water

(word equations for reaction with water)

Apparatus

Method

    1. In the fume cupboard, fill a glass trough with cold water
    2. Using litmus paper test to see if the water is acidic or basic.
    3. Select which metal you want to test 1st.
    4. Using tongs or tweasers remove a piece of metal from the oil in the containing jar
    5. On a board take a thin sliver of the alkali metal
    6. return the rest of the piece back under oil.
    7. observe the metal, especially the fresh cut edge
    8. Turn on the extractor in the fume cupboard
    9. carefully place the metal on the water,
    10. observe & note anything that happens
    11. check the aciditity / bacicitiy of the water when the reaction is complete
    12. drain the water and repeat stages for the other metals you have available

Diagram

Safety Concerns

Wear goggles throughout this demonstration

Use gloves and tongs when handling the metals

Turn on air extraction systems

Results / Observations

Write a list of the metals tested in order of their reactivities

Did you notice any colours associated with any of the metals?

What effect did the metals have on the pH of the water?

Conclusions

The alkali metals all ____________________ with water,

the reactions get more __________ as we go down the group.

These reactions change water from neutral to _______________

Comments

Characteristic colour of ____________ is ______________

The chemical formula for this reaction is

Lithium + Water → Lithium Hydroxide + Hydrogen

The same reactions happen when we replace lithium with sodium or potassium, can you write the equations

Sodium is more reactive than Lithium

Potassium is more reactive than Sodium

When these metals React with water they release Hydrogen Gas and make the water Alkali or Basic.

To check out the reaction of all the Alkali Metals, watch this video

you can carry out these experiments virtually (on a computer)

What can you say about the reactivities of the metallic elements in group I, the alkali metals ???

  • They are very reactive
  • As we go down the group the metals get more reactive

OC50 understand that Group II elements are the alkaline earth metals