Question: who organized known elements by placing them into groups of three called triads
[{'answer': 'Johann Wolfgang Dobereiner'}, {'provenance': [{'wikipedia_id': '29052228', 'title': "Döbereiner's triads", 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 763, 'bleu_score': 0.9224038209124441, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 15998522212150938112}, 'section': 'Section::::Abstract.'}]}]