( ( ( This type ) ( of bond ) ) ( ( is ( called ( a ( metallic bond ) ) ) ) . ) )
(ROOT (S (NP (NP (DT This) (NN type)) (PP (IN of) (NP (NN bond)))) (VP (VBZ is) (VP (VBN called) (NP (DT a) (JJ metallic) (NN bond)))) (. .)))
This type of bond is called a metallic bond.
(ROOT (S (NP (JJ Metallic) (NNS bonds)) (VP (VBP hold) (PRT (RP together)) (NP (NP (JJ positive) (NN metal) (NNS ions)) (CC and) (NP (PRP$ their) (JJ valence) (NNS electrons)))) (. .)))