▁layer ▁and ▁ 3 9 9   pm ▁between ▁layers ▁( compare ▁the ▁van ▁der ▁Wa als ▁radius ▁of ▁b rom ine , ▁ 1 9 5   pm ). ▁This ▁structure ▁means ▁that ▁b rom ine ▁is ▁a ▁very ▁poor ▁conduct or ▁of ▁electric ity , ▁with ▁a ▁conduct ivity ▁of ▁around ▁ 5   ×   1 0 − 1 3   Ω − 1   cm − 1 ▁just ▁below ▁the ▁mel ting ▁point , ▁although ▁this ▁is ▁better ▁than ▁the ▁essentially ▁und et ect able ▁conduct ivity ▁of ▁ch lor ine . ▁ ▁At ▁a ▁pressure ▁of ▁ 5 5   G Pa ▁( rough ly ▁ 5 4 0 , 0 0 0 ▁times ▁atmos pher ic ▁pressure ) ▁b rom ine ▁under go es ▁an ▁ins ulator - to - met al ▁transition . ▁At ▁ 7 5   G Pa ▁it ▁changes ▁to ▁a ▁face - center ed ▁orth or h omb ic ▁structure . ▁At ▁ 1 0 0   G Pa ▁it ▁changes ▁to ▁a ▁body ▁centered ▁orth or h omb ic ▁mon atomic ▁form . ▁ ▁Is ot op es ▁ ▁B rom ine ▁has ▁two ▁stable ▁is ot op es , ▁ 7 9 Br ▁and ▁ 8 1 Br . ▁These ▁are ▁its ▁only ▁two ▁natural ▁is ot op es , ▁with ▁ 7 9 Br ▁making ▁up ▁ 5 1 % ▁of ▁natural ▁b rom ine ▁and ▁ 8 1 Br ▁making ▁up ▁the ▁remaining ▁ 4 9 %. ▁Both