- Group 3 element
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7 || **Actinide sThe Group 3 elements are
chemical element s comprising the third vertical column of theperiodic table .IUPAC has not recommended a specific format for the periodic table, so different conventions are permitted and are often used for group 3. The followingd-block transition metal s are "always" considered members of group 3:*
scandium (Sc)
*yttrium (Y)When defining the remainder of group 3, four different conventions may be encountered:
* Some tables [http://periodic.lanl.gov/] include
lanthanum (La) andactinium (Ac), (the beginnings of thelanthanide andactinide series 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 mored-block -like behavior.* Some tables [http://www.webelements.com] include
lutetium (Lu) andlawrencium (Lr) as the remaining members of group 3. These elements terminate thelanthanide andactinide series, 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 seePeriodic table (wide) andPeriodic 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
lanthanide andactinide elements as included in Group 3. Lanthanides, aselectropositive trivalent metals, 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 state s) within their series than the lanthanides, and comparisons to Sc and Y are even less useful.Occurrence
Scandium, yttrium, and the
lanthanide s (except promethium) tend to occur together in the Earth's crust, and are relatively abundant compared with mostd-block metals, but often harder to extract from their ores.Biological chemistry
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.
Notes
External links
*http://periodic.lanl.gov
*http://www.webelements.com
*http://www.iupac.org/reports/periodic_table/index.html
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