<Ul> <Li> The IUPAC definition defines a transition metal as "an element whose atom has a partially filled d sub-shell, or which can give rise to cations with an incomplete d sub-shell". </Li> <Li> Many scientists describe a "transition metal" as any element in the d - block of the periodic table, which includes groups 3 to 12 on the periodic table . In actual practice, the f - block lanthanide and actinide series are also considered transition metals and are called "inner transition metals". </Li> <Li> Cotton and Wilkinson expand the brief IUPAC definition (see above) by specifying which elements are included . As well as the elements of groups 4 to 11, they add scandium and yttrium in group 3 which have a partially filled d subshell in the metallic state . These last two elements are included even though they do not (so far) seem to possess the catalytic properties which are so characteristic of the transition metals in general . Lanthanum and actinium in Group 3 are however classified as lanthanides and actinides respectively . </Li> </Ul> <Li> The IUPAC definition defines a transition metal as "an element whose atom has a partially filled d sub-shell, or which can give rise to cations with an incomplete d sub-shell". </Li> <Li> Many scientists describe a "transition metal" as any element in the d - block of the periodic table, which includes groups 3 to 12 on the periodic table . In actual practice, the f - block lanthanide and actinide series are also considered transition metals and are called "inner transition metals". </Li> <Li> Cotton and Wilkinson expand the brief IUPAC definition (see above) by specifying which elements are included . As well as the elements of groups 4 to 11, they add scandium and yttrium in group 3 which have a partially filled d subshell in the metallic state . These last two elements are included even though they do not (so far) seem to possess the catalytic properties which are so characteristic of the transition metals in general . Lanthanum and actinium in Group 3 are however classified as lanthanides and actinides respectively . </Li>

Where are transition elements on the periodic table
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