meitnerium Mt [ ] hassium Hs [ ] bohrium Bh [ ] seaborgium Sg [ ] dubnium Db [ ] rutherfordium Rf [ ] radium Ra [ ] francium Fr [ ] lutetium Lu . ytterbium Yb . thulium Tm . erbium Er .
holmium Ho . thallium Tl . mercury Hg . gold Au .
platinum Pt . iridium Ir . osmium Os . rhenium Re .
tungsten W . tantalum Ta . hafnium Hf . berkelium Bk [ ] lawrencium Lr [ ] nobelium No [ ] mendelevium Md [ ] fermium Fm [ ] einsteinium Es [ ] californium Cf [ ] curium Cm [ ] americium Am [ ] plutonium Pu [ ] neptunium Np [ ] uranium U .
protactinium Pa . thorium T . actinium Ac [ ] s-Block d-Block p-Block f-Block Figure . -Position of d- block elements in the periodic table XII U4-D-Block-Jerald XII U4-D-Block-Jerald - - - - d- Block elements composed of 3d series (4th period) Scandium to Zinc ( elements), 4d series ( th period) Yttrium to Cadmium ( elements) and 5d series ( th period) Lanthanum, Haffinium to mercury.
As we know that the group- elements Zinc, Cadmium and Mercury do not have partially filled d-orbital either in their elemental state or in their normal oxidation states. However they are treated as transition elements, because their properties are an extension of the properties of the respective transition elements. As per the IUPAC definition, the seventh period elements, starting from Ac, Rf to Cn also belong to transition metals. All of them are radioactive.
Except Actinium; all the remaining elements are synthetically prepared and have very low half life periods.