Energy is the force capable of generating an action or work. This is a Simple Guide to Understanding Energy: How many devices are there in your life, which consume energy?
The effects caused by the forces are used to identify them. If you pay attention to an object on which forces are exerted, you will observe only one effect. For example, we notice that the object moves, breaks or deforms.
The atom is the smallest particle into which an element can be divided without losing its chemical properties. Atoms are microscopic.