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.
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.
OC49 describe the reactions of the alkali metals with air and water
(word equations for reaction with water)
- In the fume cupboard, fill a glass trough with cold water
- Using litmus paper test to see if the water is acidic or basic.
- Select which metal you want to test 1st.
- Using tongs or tweasers remove a piece of metal from the oil in the containing jar
- On a board take a thin sliver of the alkali metal
- return the rest of the piece back under oil.
- observe the metal, especially the fresh cut edge
- Turn on the extractor in the fume cupboard
- carefully place the metal on the water,
- observe & note anything that happens
- check the aciditity / bacicitiy of the water when the reaction is complete
- drain the water and repeat stages for the other metals you have available
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?
The alkali metals all ____________________ with water,
the reactions get more __________ as we go down the group.
These reactions change water from neutral to _______________
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