, ▁such ▁as ▁. ▁Both ▁z inc ▁and ▁cad m ium ▁can ▁also ▁form ▁oct ah ed ral ▁complex es ▁such ▁as ▁the ▁aqu a ▁ ions ▁[ M ( H 2 O ) 6 ] 2 + ▁which ▁are ▁present ▁in ▁a que ous ▁solutions ▁of ▁sal ts ▁of ▁these ▁met als . ▁C oval ent ▁character ▁is ▁achieved ▁by ▁using ▁the ▁s ▁and ▁possibly ▁p ▁orbit als . ▁Mercur y , ▁however , ▁rarely ▁exceed s ▁a ▁coord ination ▁number ▁of ▁four . ▁Co ord ination ▁numbers ▁of ▁ 2 , ▁ 3 , ▁ 5 , ▁ 7 ▁and ▁ 8 ▁are ▁also ▁known . ▁ ▁Ext ensions ▁Although ▁cop ern ici um ▁is ▁the ▁heav iest ▁known ▁group ▁ 1 2 ▁element , ▁there ▁has ▁been ▁some ▁theoretical ▁work ▁regarding ▁possible ▁heav ier ▁group ▁ 1 2 ▁elements . ▁Although ▁a ▁simple ▁ext rap olation ▁of ▁the ▁periodic ▁table ▁would ▁put ▁element ▁ 1 6 2 , ▁un hex b ium ▁( U h b ), ▁under ▁cop ern ici um , ▁relativ istic ▁Di rac - F ock ▁calculations ▁predict ▁that ▁the ▁next ▁group ▁ 1 2 ▁element ▁after ▁cop ern ici um ▁should ▁actually ▁be ▁element ▁ 1 6 4 , ▁un hex quad ium ▁( U h q ), ▁which ▁is ▁predicted ▁to ▁have ▁an ▁electron ▁configuration ▁of ▁[ O g ] ▁ 5 g 1 8 ▁ 6 f 1 4 ▁ 7 d 1 0 ▁ 8 s 2 ▁ 8 p 1 /