elements = {\'hydrogen\': {\'number\': 1, \'weight\': 1.00794, \'symbol\': \'H\'}, \'helium\': {\'number\': 2, \'weight\': 4.002602, \'symbol\': \'He\'}} >
You should access the dictionary and add is_noble_gas as a new key to the dictionary as follows.
is_noble_gas
>>> elements['hydrogen']['is_noble_gas'] = False >>> elements['helium']['is_noble_gas'] = True