Which element has atomic number 3?
Effective atomic number interactions. For instance, lithium, atomic number 3, has two electrons in the 1s shell and one in the 2s shell. Because the two 1s electrons screen the protons to give an effective atomic number for the 2s electron close to 1, we can treat this 2s valence electron with a hydrogenic model. Mathematically, the effective atomic number Z can be calculated using methods known as "self-consistent field" calculations, but in simplified situations is just taken as the atomic number minus the number of electrons between the nucleus and the electron being considered. An alternative definition of the effective atomic number
Group 3 element 3 element. Calculations suggest that unpentpentium (Upp, element 155) could also be the next group 3 element. If lanthanum and actinium are considered group 3 elements, then element 121, unbiunium (Ubu), should be the fifth group 3 element. The element is calculated have electronic configuration of [Og]8s8p, which is not associated with transition metals, without having a partially filled d-subshell. No experiments have been performed to create unpenttrium, unbiunium or any element that could be considered the next group 3 element; however, unbiunium is the element with the lowest atomic number that has not been tried to be created and