Is the bond between the b and the h in bh4- a coordinate covalent bond?
No, the bond between the "b" and the "h" in the BH4- ion is not a coordinate covalent bond. It is a regular covalent bond in which both the boron atom and the hydrogen atom contribute electrons to form the bond.
Coordinate covalent bonds occur when one atom donates a pair of electrons to another atom to form a bond. In the case of BH4-, the boron atom does not donate a pair of electrons to the hydrogen atom; instead, both atoms contribute electrons to form the bond.
To determine whether the bond between the b (boron) and the h (hydrogen) in BH4- (tetrahydroborate) is a coordinate covalent bond, we need to consider the electronic configuration and bonding in this species.
The BH4- ion consists of a central boron atom bonded to four hydrogen atoms. Boron has an atomic number of 5, which means it has 5 electrons in its neutral state. In BH4-, boron has lost 3 electrons to attain a stable octet configuration, leaving it with 2 valence electrons.
Each hydrogen atom contributes 1 electron, and since there are four hydrogen atoms, we have a total of 4 electrons from hydrogen. Hence, the BH4- ion has a total of 2 + 4 = 6 electrons.
To evaluate whether the boron-hydrogen bond is a coordinate covalent bond, we look at the Lewis structure of BH4-. In this structure, the boron atom has a lone pair of electrons, which it can use to form a bond with the hydrogen atom. This type of bond is known as a coordinate covalent bond.
To represent a coordinate covalent bond, you would show an arrow originating from the lone pair on boron pointing towards the hydrogen atom. The arrow indicates the movement of a pair of electrons from the boron atom to form the bond with hydrogen.
Therefore, yes, the bond between the boron and hydrogen in BH4- is a coordinate covalent bond.