Atomic number: 103

Symbol: Lr (originally Lw) 

Category: actinide 

Density at 25°C: solid:  n/a

This is the last of the actinides. This element has a half life of 3.5 hours. Test have shown that it is chemical similar to lutetium , which sits just above it on the periodic table. Only a few atoms were produced initially in laboratories in Dubna and Berkeley.