From the following list of orbital combinations, how many can successfully form a head-on -bond (ass — Chemical Bonding Chemistry Question
Question
From the following list of orbital combinations, how many can successfully form a head-on $\sigma$ -bond (assuming the optimal internuclear axis is chosen for each pair)? $s+s$, $s+p_x$, $p_x+p_x$, $p_z+p_z$, $d_{z^2}+d_{z^2}$, $p_x+p_y$, $s+d_{xy}$, $p_y+p_y$.
💡 Solution & Explanation
To form a $\sigma$ -bond, orbitals must overlap axially. $s+s$ (any axis), $s+p_x$ (x-axis), $p_x+p_x$ (x-axis), $p_z+p_z$ (z-axis), $d_{z^2}+d_{z^2}$ (z-axis), and $p_y+p_y$ (y-axis) can all form $\sigma$ -bonds. Orthogonal orbitals like $p_x+p_y$ always yield zero overlap. The $d_{xy}$ orbital has lobes between axes, so $s+d_{xy}$ yields zero overlap. Total = 6.