A component’s reactivity depends on the number of electron shells it has. The more electron shells, the less attractive appreciation for the core the electrons on the external shells have. Along these lines, they can without much of a stretch travel to other artificially appealing particles (synthetically alluring implying that their external electron shells are inadequate and just need a couple of pretty much electrons to be finished.)
As you might be aware, the further down you come (the y pivot), the more electron shells the components have and aside from the respectable gasses, the temporary metals are the most unresponsive gathering on the occasional table (because of having tolerably adjusted external shells) which are arranged towards the focal point of the table. In this way, the farther you go from those components, the reactivity of the components increases.
Antacid metals (arranged far away from temporary metals and respectable gasses) are the most responsive natural gathering. Cesium is second from the lower part of this gathering, with 6 electron shells, so it fits every one of the qualities of a responsive molecule, hence making it the most receptive component.
Final Answer: Hence, Alkali metals (situated far away from transitional metals and noble gases) are the most reactive elemental group.