Question: what is a row across the periodic table called
[{'answer': 'period', 'provenance': [{'wikipedia_id': '23053', 'title': 'Periodic table', 'start_paragraph_id': 1, 'start_character': 4, 'end_paragraph_id': 1, 'end_character': 10, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]