Group |(Akali Metals)

The group elements have the following properties:
1.They are soft and silvery solids.
2.The elements have low densities and low melting points.
3.They react vigorously with cold water to form an akaline solution of the metal hydroxide and hydrogen gas.
4.The elements burn brightly when heated in chlorine gas.The product is a white solid of metal chloride (e.g. NaCl, KCl)

Lithium
Observation for (3): Fast reaction
Equation for reaction(3): 2Li + 2H2O -> 2LiOH + H2

Observation for (4): Burns with bright flame;white solid produced.
Equation for reaction(4): 2Li + Cl2 ->2LiCl (white solid)


Sodium
Observation for (3): Very fast reaction;sometimes an explosion
Equation for reaction(3): 2Na + 2H2O ->2NaOH + H2

Observation for (4): Burns with bright flame;white solid produced;reaction more vigorous than lithium
Equation for reaction(4): 2Na + Cl2 ->2NaCl (white solid)

Potassium
Observation for (3): Immediate explosion
Equation for reaction(3): 2K + 2H2O ->2KOH + H2

Observation for (4): Burns with bright flame;white solid produced;reaction more vigorous than sodiumEquation for reaction(4): 2K + Cl2 ->2KCl (white solid)

5.Atoms of group elements have one electron in their outer shells.
6.Atoms of the elements lose one electron to form ions with a charge of +1 im compounds.
For Example:
Electronic Configuration of Sodium atom: 2.8.1
Electronic Configuration of Sodium ion,Na+: 2.8

The following changes take place down the group:
1.The melting points of the elements decrease.
2.The elements become more reactive.They react more vigorously with water and chlorine.

Properties of other elements can be predicted from:
-known properties of lithium,sodium and potassium
-the changes down the group

For example, predict how you would expect rubidium(Rb) to react with water, and write an equation for the reaction. Rubidium is below potassium in group .

-Rubidium would be expected to react with water to produce hydrogen gas and a solution of rubidium hydroxide,like the other elements in the group.
So the equation would be: 2Rb + 2H2O -> 2RbOH + H2
-The trend in group is for the elements to become more reactive down the group.So rubidium would be expected to be more reactive than potassium.Hence it would explode with water.