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The Group 3 elements are chemical elements comprising the third vertical column of the periodic 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 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. (See group number of lanthanides and actinides):
- Some tables [1] include lanthanum (La) and actinium (Ac), (the beginnings of the lanthanide and actinide 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 more d-block-like behavior.
- Some tables [2] include lutetium (Lu) and lawrencium (Lr) as the remaining members of group 3. These elements terminate the lanthanide and actinide series, respectively. This is the arrangement preferred by Glenn T. Seaborg. Since the f-shell is nominally full in the ground state electron configuration for both of these metals, they behave more like d-block metals than any of the lanthanides and actinides do, 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 [3] refer to lutetium, lawrencium, and the 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 lutetium, lawrencium, and the entire 28 lanthanide and actinide elements as included in Group 3. Lanthanides, as electropositive trivalent metals, all have a closely related chemistry, and all show many similarities to Sc and Y.
- The fourth alternative is to exclude lutetium, lawrencium, and the lanthanides and actinides from 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.
[edit] Occurrence
Scandium, yttrium, the and the lanthanides (except promethium) tend to occur together in the Earth's crust, and are relatively abundant compared with most d-block metals, but often harder to extract from their ores.
[edit] External links
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