A classmate sketches the following Lewis diagram for the tetrahydroborate ion, BH₄⁻:…
CHEMISTRY · Single correct · A Level · Chemistry · Bonding · Bonding
Problem
A classmate sketches the following Lewis diagram for the tetrahydroborate ion, BH₄⁻:
H–B–H
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H H
The student places no brackets or overall charge on the structure and shows no lone pairs. Which of the following best describes the primary consequence of omitting the bracketed –1 charge in the diagram?
(a) The structure now implies boron carries a +1 formal charge, misrepresenting the actual electron distribution.
(b) The electron count for the entire structure is underestimated by one electron, resulting in an apparent violation of boron's octet.
(c) Leaving off the bracket suggests that the negative charge resides on one hydrogen, so one B–H bond should instead be drawn as a lone pair on hydrogen.
(d) With the missing charge, students would predict only three electron domains around boron and therefore a trigonal-planar geometry instead of the correct tetrahedral shape.