Ninu kemistri, ifagbaramerindimu ni ipo atomu kan to ni with four elektronu merin ti won wa fun isopo kemika ajofagbadimu ni ibi idimu re (igba elektronu to bosodejulo).. 
Freiburg jẹ́ ìlú ní ìpínlẹ̀ Baden-Württemberg, ní Jemani.. 