Symbol: Rf

Category: (transition metal)

Density at 25°C: solid:  n/a

This is the first element in along the last row of the main part of the periodic table. Period 7 Group 4. The properties of all these elements are not well characterised and may be slightly disputed.  The most stable isotope has a half life of about 1.3 hours. 

Named after Ernest Rutherford, a New Zealand physicist. It was not named until 1997.