The elements in Group 1 are:
Chemical Name |
Chemical Symbol |
Atomic Number |
Lithium |
Li |
3 |
Sodium |
Na |
11 |
Potassium |
K |
19 |
Rubidium |
Rb |
37 |
Caesium |
Cs |
55 |
Francium |
Fr |
87 |
The alkali metals have 1 valence electron and are the most reactive metals.
All alkali metals react violently with water, releasing hydrogen gas and forming hydroxides. The hydroxides give alkaline solutions.
Group 1 element + water → alkali + hydrogen
Example:
sodium + water → sodium hydroxide + hydrogen
2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g)
Check the videos below to see how each alkali metal reacts with water. You will notice that the alkali metals get more reactive as you go down the group.
Alkali Metal |
How it reacts with water? |
lithium |
a lot of fizz around the floating metal |
sodium |
shoots around on the surface of the water |
potassium |
melts and the hydrogen bursts into flame |
rubidium |
sparks fly |
caesium |
violent explosion |
When heated alkali metals are placed into jars of chlorine gas, they will burst into flames. They will burn brightly, giving white solids called chlorides.
Example:
Sodium + chloride → sodium chloride
Na + Cl → NaCl
Sodium chloride is also known as common salt. (It is the salt that we put in our food.) The chloride dissolves in water to give a colorless solution.
How do Alkali Metals react with Oxygen?
When heated alkali metals are placed into jars of oxygen gas, they will burst into flames. They will burn brightly, giving white solids called oxides.
Example:
Sodium + oxygen → sodium oxide
4Na + O2 → 2Na 2O
The oxide dissolves in water to give a colorless alkaline solution.
Alkaline Metal |
Color of flame when react with oxygen |
Lithium |
red |
Sodium |
yellow |
Potassium |
lilac |
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