Alkali metal — ক্ষার ধাতু
Alkali metals are the soft Group 1 metals (Li to Fr) with one valence electron and a passion for water.
Definition
The alkali metals — lithium, sodium, potassium, rubidium, caesium and francium — fill Group 1, each carrying a single valence electron it gives away easily to form +1 ions. They are soft enough to slice with a knife, shine briefly before tarnishing in air, and are light enough that lithium, sodium and potassium float on water. That water reaction is their signature: they fizz violently, release hydrogen gas and leave behind an alkali solution, which is how the family got its name — and why they are stored under oil.
For example
In the school lab, a pea-sized sodium piece dropped in water skates around the surface, hisses hydrogen and may end in a small golden flame — which is why your teacher uses tweezers and a safety screen.