In sociology and psychology, some definitions include only consciously malignant forms of discrimination. Some definitions of racism also include discriminatory behaviors and beliefs based on cultural, national, ethnic, caste, or religious stereotypes.
A cell is much, much larger than an atom. A typical animal cell might be 10,000 times as wide, long, and tall as a typical atom, or about 1 trillion times the volume of an atom. Another way to arrive at this answer is to consider the fact that cells are made up of atoms, so the atoms must therefore be smaller.
(How do atoms form?) What is the biggest atom? The smallest atom? If by biggest and smallest, you mean mass (which is a measure of how much matter is there), then the smallest is the hydrogen atom with one proton and one electron. Since electrons are about 2000 times less massive than protons (and neutrons), then the mass of an atom is mostly from the protons and neutrons.