Periodic table. Computer illustration representing the periodic table of the elements as a wheel structure. The radiating spokes are the groups and are colour coded. The heights of the columns represent the elements' atomic numbers, being the numbers of protons in their nuclei. The elements in any one group share many chemical and physical properties. At the wheel's centre is the first element, hydrogen, (H, white). At the end of each spoke, the elements are unnamed, and only their atomic numbers are shown, from 110-120. The trans- ition elements (upper left, orange) and the Lanth- inides and Actinides (upper right) are blocks of elements with predictably varying properties.