Lithium is the first element in group 1 of the Periodic Table. The observations for the reaction of lithium and water are:
- fizzing (hydrogen gas is released)
- Lithium floats and moves around on the water
- Lithium disappears
The reactions of sodium or potassium and water are similar but more vigorous:
- When sodium reacts with water, the sodium also melts.
- When potassium reacts with water, the potassium also catches fire with a lilac flame.
When the group 1 metals react with air they show a similar trend in reactivity as we go down the group of the Periodic Table.
Therefore, as we go down group 1 (increasing atomic number), the elements become more reactive: Li<Na<K<Rb<Cs<Fr