The minimum amount of energy required for effective collisions between reacting particles is known as

Step 1: Analyze the question The question asks for the name of the minimum energy that colliding particles must have for a collision to lead to a reaction (an "effective" collision).

Step 2: Explain the concept According to collision theory, particles must collide before they can react. However, not every collision produces a reaction. For a collision to be effective, two conditions must be met:

1. The particles must collide with the correct orientation.
2. The particles must have at least a certain minimum energy, called the activation energy (Ea).

If the colliding particles have less energy than this, they simply bounce off each other unchanged.

Step 3: Check each option

• A. Activation energy is the minimum energy needed for effective collisions and for a reaction to occur. This matches the question.
• B. Bond energy is the energy needed to break a particular bond, or released when it forms. It is not the threshold for effective collisions.
• C. Kinetic energy is the energy a particle has because of its motion. Particles have kinetic energy, but this is not the minimum threshold.
• D. Potential energy is stored energy due to position or composition. It does not define the minimum energy for effective collisions.

Step 4: Answer The correct option is A. activation energy.

Exam tip: Remember "Activation = Actually react". Whenever you see "minimum energy needed to start a reaction" or "energy barrier," think activation energy. It is also why catalysts speed up reactions: they provide an alternative pathway with a lower activation energy, so more collisions become effective.