Only effective collisions lead to the formation of products. It means that collisions in which molecules collide with sufficient kinetic energy and proper orientation lead to a chemical change because it facilitates the breaking bonds between the reactant molecules and formation of the products.
e.g., formation of methanol from bromomethane depends upon the orientation of the reactant molecules.
$$
\mathrm{CH}_3 \mathrm{Br}+\mathrm{OH}^{-} \longrightarrow \mathrm{CH}_3 \mathrm{OH}+\mathrm{Br}^{-}
$$







The proper orientation of reactant molecules lead to bond formation whereas improper orientation do not result into formation of products.