Question

if bond order comes out in decimal as in H2+ then what is covalent bond b/w H2+ and if a B.O IS -ve of a molecule then what is covalent bond b/w atoms

Answer 1

If the value of bond order is positive, it indicated a stable molecule and if the value of bond order is negative or zero, it means that molecule is unstable. But the type of bonding remains covalent in nature

Hydrogen molecule ion (H₂⁺)
This is formed by the combination of hydrogen atom containing one electron and hydrogen ion having no electron. Therefore, this ion has only one electron.
The electronic configuration of the molecule is: H₂⁺ : ($\sigma$1s)¹
Bond order = $\frac{N_b-N_a}{2}=\frac{1-0}{2}=\frac{1}{2}$

The positive value of bond order indicates that the molecule is stable. The presence of unpaired electron in the molecule give rise to fractional bond order, indicating that it is paramagnetic molecule.