Caesium is a Metal which can combust spontaneously with air. It is used for atomic clocks.
Never call Caesius fat, or you’re in trouble. It is actually quite athletic: It can hit a traffic light with a tomato from half a mile, making it turn to red. Also it is obsessed with the clock: It asks everyone what time it is. Who can’t answer quickly enough, will get pelted with whatever is lying around.
Potassium is an ambivalent element: highly reactive on the one hand – it explodes on contact with water – on the other hand every living being needs it for survival.
Kali the monster is a manic creature. Quarrelsome and vengeful it finds a fly in every ointment and can drive othe monsters up the wall. But whoever is in real need can count on her.