Drawing the Lewis Structure for BH4-

Viewing Notes:

  • With BH4- be sure to add an additional valence electron to your total because of the negative sign.
  • There are a total of 8 valence electrons in BH4-.
  • Be sure to put brackets and a negative sign around the BH4- Lewis structure to show that it is an ion.

Transcript: This is the BH4- Lewis structure. For BH4-, we have 3 electrons for Boron, 1 for Hydrogen but we have 4 Hydrogens, and then we need to add one more for the negative charge, for a total of 3+4+1: 8 valence electrons. We'll put the Boron at the center. Hydrogens always go on the outside, and we have 4 Hydrogens. We'll place them around the Boron like this. We have a total of 8 valence electrons. We'll put 2 between atoms to form chemical bonds--we've used 6, and we've used all our valence electrons. Hydrogen only needs 2 valence electrons to have a full outer shell, so each of the Hydrogens has its outer shell full. And the Boron has 8 valence electrons. So we've used all 8 valence electrons for the BH4 Lewis structure, and each of the atoms has a full outer shell. One last thing we need to do is put brackets around the ion to show that it has a negative charge.

So that's the Lewis structure for BH4-, the tetrahydroborate ion. This is Dr. B., and thanks for watching.