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Group number of lanthanides and actinides



Group 3 or ungrouped
Period
*
**
6 *Lanthanides
57
La
58
Ce
59
Pr
60
Nd
61
Pm
62
Sm
63
Eu
64
Gd
65
Tb
66
Dy
67
Ho
68
Er
69
Tm
70
Yb
71
Lu
7 **Actinides
89
Ac
90
Th
91
Pa
92
U
93
Np
94
Pu
95
Am
96
Cm
97
Bk
98
Cf
99
Es
100
Fm
101
Md
102
No
103
Lr

IUPAC has not recommended a specific format for the periodic table, so different conventions are permitted and are often used for the group number of lanthanides and actinides. There is no pre-existing physical entity for a "group" of elements. The notion is simply a convenient classification, since some elements have similar periodicities in their properties. This allows them to be arranged in columns that also happen to correspond with electron configurations.

  • Some tables [2] include lutetium, (Lu) and lawrencium, (Lr) in group 3. These elements terminate the lanthanide and actinide series, respectively. Since the f-shell is nominally full in the ground state electron configuration for both 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).)

Additional recommended knowledge

Some tables [3] refer to all lanthanides and actinides by a marker in group 3. This is the periodic table used by Wikipedia. A third and fourth alternative are suggested by this arrangement:

  • The third alternative is to regard all 30 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 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.



Explanation of above periodic table slice: Lanthanide series Actinide series atomic number in black are solids solid borders are primordial elements (older than the Earth) dashed borders are naturally radioactive elements dotted borders are synthetic elements
 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Group_number_of_lanthanides_and_actinides". A list of authors is available in Wikipedia.
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