Alkali Metals
Learning Objectives:
• BRONZE: Identify the location of alkali metals in the periodic
table and describe alkali metals as: a) soft metals b) metals with
comparatively low melting points (E-C)
• SILVER: Describe the reactions of lithium, sodium and potassium
with water to form hydroxides which are alkaline, and hydrogen
gas (C-B)
• GOLD: Describe the pattern in reactivity of the alkali metals
lithium, sodium and potassium with water and use this pattern to
predict the reactivity of other alkali metals H and explain the
pattern. (B-A*)
Periodic Table
Group 1
Alkali Metals
Why are they called the ‘alkali metals’?
The alkali metals are so
reactive that they have to
be stored in oil.
Why do we need to do
this?
Alkali metals are different to
most other metals.
Alkali metals are soft enough to be cut with a knife, and
the most common alkali metals, lithium, sodium and
potassium, all float on water.
The elements in group 1 also react with water and form
alkaline compounds. This is why they are called alkali
metals.
Reaction of metals with water
metal
metal
hydroxide
water
hydrogen
Reaction of metals with water
Sodium
water
Sodium
_______
hydroxide
hydrogen
Symbol Equations
Sodium + water  sodium hydroxide + hydrogen gas
Na
H2O
NaOH
H2
Is this equation balanced?
2Na + 2H2O  2NaOH + H2
What is the electron structure of alkali metals?
How many electrons are in the outer shell of alkali metals?
This means that:
 They are found in group 1
of the periodic table.
 They have similar
physical and chemical
properties.
 They can readily lose
the outer shell electron
to form positive ions
with a +1 charge and a
full outer shell.
lithium
2,1
sodium
2,8,1
potassium
2,8,8,1
Lithium
Li
Reactivity Series
Sodium
Na
Potassium
K
Rubidium
Rb
Caesium
Cs
Francium
Fr
As you go down the
group the elements
get more reactive!
They get more reactive but
why???
Explanation
• The greater the number of electron shells will
mean that the one electron on the outer shell will
be further from the nucleus.
• The force between the positive and negative
charges will decrease the further away the outer
electron is, so the outer electron in a caesium atom
is not held as strongly as the outer electron in a
sodium atom, so this is why it is more reactive.
• The more shells there are between the outer
electron and the nucleus the more shielding there
is, this also makes the electron easier to remove.