- Group 3 element
|| Group 3/ungrouped
7 || **
The Group 3 elements are
chemical elements comprising the third vertical column of the periodic table. IUPAChas not recommended a specific format for the periodic table, so different conventions are permitted and are often used for group 3. The following d-block transition metals are "always" considered members of group 3:
When defining the remainder of group 3, four different conventions may be encountered:
* Some tables [http://periodic.lanl.gov/] include
lanthanum(La) and actinium(Ac), (the beginnings of the lanthanideand actinideseries of elements, respectively) as 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 resulting in more d-block-like behavior.
* Some tables [http://www.webelements.com] include
lutetium(Lu) and lawrencium(Lr) as the remaining members of group 3. These elements terminate the lanthanideand actinideseries, respectively. Since the f-shell is nominally full in the ground state electron configuration for both of these metals, they behave most like d-block metals out of all the lanthanides and actinides, and thus exhibit the most similarities in properties with Sc and Y. For Lr, this behavior is expected, but it has not been observed because sufficient quantities are not available. ("Also see Periodic table (wide)and Periodic table (extended).")
Some tables [http://www.iupac.org/reports/periodic_table/index.html] refer to "all" lanthanides and actinides by a marker in group 3. A third and fourth alternative are suggested by this arrangement:
* The third alternative is to regard all 30
lanthanideand actinideelements as included in Group 3. Lanthanides, as electropositive trivalentmetals, all have a closely related chemistry, and all show many similarities to Sc and Y.
* The fourth alternative is to include none of the lanthanides and actinides in group 3. The lanthanides possess additional properties characteristic of their partially-filled f orbitals which are not common to Sc and Y. Furthermore, the actinides show a much wider variety of chemistry (for instance, in range of
oxidation states) within their series than the lanthanides, and comparisons to Sc and Y are even less useful.
Scandium, yttrium, and the
lanthanides (except promethium) tend to occur together in the Earth's crust, and are relatively abundant compared with most d-blockmetals, but often harder to extract from their ores.
Group 3 elements are generally hard metals with low aqueous solubility, and have low availability to the biosphere. No group 3 has any documented biological role in living organisms. The radioactivity of the actinides generally makes them highly toxic to living cells.
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