Rubidium (Rb) must lose one electron to achieve a noble gas configuration corresponding to krypton (Kr).

Rubidium (Rb) must lose two electrons to achieve a noble gas configuration corresponding to krypton (Kr).

Rubidium (Rb) must lose one electron to achieve a noble gas configuration corresponding to xenon (Xe).

Rubidium (Rb) must lose two electrons to achieve a noble gas configuration corresponding to xenon (Xe).