Mention the basic tendency of an atom which makes it combine with other atoms
Besides chaos, everything in this world wants stability. The same is the case with atoms. For atoms, stability means having the electron arrangement of inert gas, i.e. octet in the outermost shell. Helium has two electrons (duplet), while all other inert gases, i.e. neon, argon, krypton, xenon, and radon have eight electrons (octet) in the outermost shell.