( ( ( ( ( ( ( The ( vertical columns ) ) ( of ( the table ) ) ) ( are ( called groups ) ) ) , ) and ) ( ( the ( horizontal rows ) ) ( are ( called periods ) ) ) ) . )
(ROOT (S (S (NP (NP (DT The) (JJ vertical) (NNS columns)) (PP (IN of) (NP (DT the) (NN table)))) (VP (VBP are) (VP (VBN called) (NP (NNS groups))))) (, ,) (CC and) (S (NP (DT the) (JJ horizontal) (NNS rows)) (VP (VBP are) (VP (VBN called) (NP (NNS periods))))) (. .)))
The vertical columns of the table are called groups, and the horizontal rows are called periods.
(ROOT (S (NP (NP (NNP Group) (CD 13)) (PP (IN of) (NP (DT the) (JJ periodic) (NN table)))) (VP (VBZ is) (ADVP (RB also)) (VP (VBN called) (NP (DT the) (DT the) (NN boron) (NN group)))) (. .)))