In a regular B_(12) icosahedran : (a) How many boron atoms are equidistant from a given boron atom ? (b) How many edges are there ? ( c) How many valence electrons are there ? (d) Can each edge line represent pair bond ? ( e) Explain the type of bonding involved in elemental boron ?

In a regular B_(12) icosahedran : (a) How many boron atoms are equidi

1.	In a regular B_(12) icosahedran : (a) How many boron atoms are equidistant from a given boron atom ? (b) How many edges are there ? ( c) How many valence electrons are there ? (d) Can each edge line represent pair bond ? ( e) Explain the type of bonding involved in elemental boron ?
Answer» Solution :In a regular `B_(12)` icosahedran : (a) Five boron atoms are equidistant from a given boron atom. (b) There are `30` edges, i.e. `5` from the TOP B-atom, `5` around the upper pentagon, `10` from the upper pentagon to the low, `5` around the lower pentagon and `5` to the bottom boron atom. ( c) Valence shell electronic configuration of `B` is `2 s^(2) 2p^(1)`, so each boron atom has `3` valence electrons. Total number of valence electrons in `B_(12)` icosahedra `= 3 xx 12 = 36` electrons. (d) No, there are `30` edges in `B_(12)` icosahedra, so the total electron should be `30 xx 2 = 60` electrons. SINCE there are not `60` electrons. hence each EDGE line cannot represent an electron pair. ( e) There MUST be some `(3c, 2e)` bridge bonding, just as in diborane.