Group 4 element doses and does not play any natural role inside the human body. Zirconium powder can cause irritation, but only contact with the eyes requires medical attention. OSHA recommendations for zirconium are 5 mg/m time weighted average limit and a 10 mg/m short-term exposure limit. Only limited data exists on the toxicology of hafnium. Group 4 element Group 4 is a group of elements in the periodic table. It contains the elements titanium (Ti), zirconium (Zr), hafnium (Hf) and rutherfordium (Rf). This group lies in the d-block of the periodic table. The group itself has not acquired a trivial name; it
Periodic table German chemist Julius Lothar Meyer independently published their periodic tables in 1869 and 1870, respectively. Mendeleev's table was his first published version; that of Meyer was an expanded version of his (Meyer's) table of 1864. They both constructed their tables by listing the elements in rows or columns in order of atomic weight and starting a new row or column when the characteristics of the elements began to repeat. The recognition and acceptance afforded to Mendeleev's table came from two decisions he made. The first was to leave gaps in the table when it seemed that the corresponding element had