Size comparison (IMAGE) University of Tokyo Caption The familiar periodic table of elements with each kind of atom shown as colored balls. The size of each atom in the CPK model (above) is larger than those in the Z-correlated model (below), as it is based on the distribution of electrons around an atom rather than on the size of the nucleus itself. This is important in electron microscopy where the electron cloud is not visible. Credit © 2021 Nakamura, Harano et al. Usage Restrictions Credit © 2021 Nakamura, Harano et al. License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.