query: what did niels bohr discover about the atomic structure?
answers: [ ' B o h r b e g a n t o d e v e l o p a m o d e l o f t h e a t o m i n w h i c h e l e c t r o n s w e r e d i s p o s e d i n r i n g s a r o u n d t h e n u c l e u s - - a f i r s t s t e p t o w a r d s a n e x p l a n a t i o n o f a t o m i c s t r u c t u r e . ' ]