What is the predicted bond angles in the borane molecule? What is the hybridization on Boron in a molecule of Borane
The correct answer and explanation is:
Correct Answer:
The predicted bond angles in the borane (BH₃) molecule are approximately 120 degrees.
The hybridization of boron in borane is sp².
Explanation:
Borane (BH₃) is a simple molecule consisting of one boron atom bonded to three hydrogen atoms. Boron has an atomic number of 5, which means it has three valence electrons. In borane, these three valence electrons form three sigma bonds with three hydrogen atoms.
Boron in BH₃ uses sp² hybridization to form these bonds. This hybridization involves the mixing of one s orbital and two p orbitals from the boron atom, creating three equivalent sp² hybrid orbitals. Each of these orbitals overlaps with the 1s orbital of a hydrogen atom to form a sigma bond.
Because sp² hybrid orbitals arrange themselves in a planar triangular geometry to minimize electron repulsion, the molecule adopts a trigonal planar shape. This results in bond angles of 120 degrees between the hydrogen atoms. These bond angles are predicted by the Valence Shell Electron Pair Repulsion (VSEPR) theory, which states that electron pairs around a central atom will orient themselves as far apart as possible to minimize repulsion.
It is important to note that BH₃ is electron-deficient. The boron atom in BH₃ has only six electrons in its valence shell, not the full octet. This electron deficiency makes BH₃ highly reactive and unstable under normal conditions. It readily forms dimers or reacts with Lewis bases to complete its octet. For instance, borane commonly exists as diborane (B₂H₆) in nature due to its tendency to stabilize through bonding interactions.
In summary, borane has bond angles of approximately 120 degrees and boron is sp² hybridized, forming a trigonal planar structure around the central atom.