Mass number number of protons in a nucleus, and thus uniquely identifies an element. Hence, the difference between the mass number and the atomic number gives the number of neutrons ("N") in a given nucleus: . The mass number is written either after the element name or as a superscript to the left of an element's symbol. For example, the most common isotope of carbon is carbon-12, or , which has 6 protons and 6 neutrons. The full isotope symbol would also have the atomic number ("Z") as a subscript to the left of the element symbol directly below the mass number:
Asymmetric C-element Asymmetric C-element Asymmetric C-elements are extended C-elements which allow inputs which only effect the operation of the element when transitioning in one of the directions. Asymmetric inputs are attached to either the minus (-) or plus (+) strips of the symbol. The common inputs which effect both the transitions are connected to the centre of the symbol. When transitioning from zero to one, the C-element will take into account the common and the asymmetric plus inputs. All these inputs must be high for the up transition to take place. Similarly when transitioning from one to zero the C-element will take