Reactivity series — সক্রিয়তা ধারা
The reactivity series ranks metals from most to least reactive — potassium at the top, gold at the very bottom.
Definition
The reactivity series lines up metals in order of how eagerly they give away electrons: potassium, sodium, calcium, magnesium, aluminium, zinc, iron, lead, hydrogen, copper, mercury, silver, gold. Metals above hydrogen push it out of dilute acids as bubbles; those below sit unmoved. A higher metal displaces a lower one from its salt solution, and the series even hints how each metal is won from its ore — the most reactive must be extracted by electrolysis, while gold is found free and shiny in riverbeds.
For example
Potassium fizzes and flares the moment it meets water; a gold bangle stays bright through years of washing — the two ends of the series, both at home in your daily life.