According to the $VB$ theory,when is a bond not formed between two atoms? Give examples.

(N/A) According to the $VB$ theory,a bond is not formed if the two atomic orbitals are not oriented along the common internuclear axis,as this leads to zero overlap.
Examples:
$1$. The overlap between an $s$-orbital and a $p_x$-orbital oriented perpendicular to the internuclear axis ($z$-axis) results in zero overlap.
$2$. The overlap between a $p_x$-orbital and a $p_y$-orbital oriented along the same internuclear axis ($z$-axis) also results in zero overlap.