( ( Columns ( of ( the ( periodic table ) ) ) ) ( ( ( ( ( contain elements ) ( with ( ( the ( same number ) ) ( of electrons ) ) ) ) and ) ( are ( called groups ) ) ) . ) )
(ROOT (S (NP (NP (NNS Columns)) (PP (IN of) (NP (DT the) (JJ periodic) (NN table)))) (VP (VP (VBP contain) (NP (NNS elements)) (PP (IN with) (NP (NP (DT the) (JJ same) (NN number)) (PP (IN of) (NP (NNS electrons)))))) (CC and) (VP (VBP are) (VP (VBN called) (NP (NNS groups))))) (. .)))
Columns of the periodic table contain elements with the same number of electrons and are called groups .
(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)))) (. .)))