What is the size of an atom?

The size of an atom is about 10^-10 meters or 10^-8 centimeters. Atomic size is measured as the distance between the center of the nucleus of an atom and its outermost shell. Atoms of different elements vary in size but 10^-10 meters is considered as the rough size estimate for all atoms. 

Individual isolated atoms are extremely small and the location of the electrons that surround the atom’s nucleus can’t be determined. This makes it difficult to measure the size of isolated atoms. The estimated atomic size is based on the assumption that the radius of an atom is half the distance between adjacent atoms in a solid. These measurements are called metallic radii as this measuring technique is best suited to elements that are metals.