<Li> Lanthanum and actinium are sometimes considered the remaining members of group 3 . In their most commonly encountered tripositive ion forms, these elements do not possess any partially filled f - orbitals, thus continuing the scandium--yttrium--lanthanum--actinium trend, in which all the elements have relationship similar to that of elements of the calcium--strontium--barium--radium series, the elements' left neighbors in s - block . However, different behavior is observed in other d - block groups, especially in group 4, in which zirconium, hafnium and rutherfordium share similar chemical properties lacking a clear trend . It has however been argued that this is irrelevant because the principle of increasing basicity down the table is more fundamental, and because the behavior of the group 3 elements is more similar to their s - block neighbors than their d - block neighbors . </Li> <Li> In other tables, lutetium and lawrencium are classified as the remaining members of group 3 . In these tables, lutetium and lawrencium end (or sometimes succeed) the lanthanide and actinide series, respectively . Since the f - shell is nominally full in the ground state electron configuration for both of these metals, they behave most similarly to other period 6 and period 7 transition metals compared to the other lanthanides and actinides, and thus logically exhibit properties similar to those of scandium and yttrium . However, this resemblance in not unique to lutetium and lawrencium, but is common among all the late lanthanides and actinides . </Li> <Li> Some tables, including the one published by IUPAC refer to all lanthanides and actinides as being in group 3: 30 lanthanide and actinide elements together with scandium and yttrium . Lanthanides, as electropositive trivalent metals, all have a closely related chemistry, and all show many similarities to scandium and yttrium, but they also show additional properties characteristic of their partially filled f - orbitals which are not common to scandium and yttrium . </Li> <Li> Exclusion of all elements is based on properties of earlier actinides, which show a much wider variety of chemistry (for instance, in range of oxidation states) within their series than the lanthanides, and comparisons to scandium and yttrium are even less useful . However, these elements are destabilized, and if they were stabilized to more closely match chemistry laws, they would be similar to lanthanides as well . Also, the later actinides from californium onwards behave more like the corresponding lanthanides, with only the valence + 3 (and sometimes + 2) shown . </Li>

Properties of group 3 elements in the periodic table