The atom is the smallest particle of an element that retains it's characteristics. Sub-atomic particles such as protons, neutrons and electrons form the atom and it is the amount of each of these sub-atomic particles that make the element that element.
It can be as small as a grain of sand or as large as a boulder. Sediment moves from one place to another through the process of erosion. Erosion is the removal and transportation of rock or soil. Erosion can move sediment through water, ice, or wind.
