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.
The smallest atom is a hydrogen atom (37 picometers) whereas some larger atoms more than 5 times larger (lanthanum is 187 picometers). If the atom is an ion, it will also change it's radius significantly (positive ions are smaller and negative ions are larger than the neutral atom).