Orientation of Reactants

Well, we've learned that one of the criteria for a effective reaction occur, is that the particles must collide with the proper orientation.

This proper orientation is also known a collision geometry.

The following chemical equation illustrate why this criteria is essential:

NO(g) + NO3(g) = NO2(g) + NO2(g)

When the particles of NO(g) collides with particles of NO3(g), NO2(g) particles will be formed. However, not all the collisions between these particles will generate the product.

Analyse the following image

As you can see, out of the five different types of collision, only one is geometrical, and will produce other particles.