Subject
actinide
3
chromium
3
hafnium
3
lanthanum
manganese
3
metal organic compound
molybdenum
3
tantalum
3
technetium
3
titanium
3
vanadium
zirconium
3
cobalt
2
iron
2
nickel
2
niobium
2
osmium
2
palladium
2
platinum
2
rare earth organic compound
2
rhenium
2
ruthenium
2
tungsten
2
actinium
1
rare earth
1
rare earth compound
1
rhenium compound
1
rhodium
1
scandium
1
yttrium
1