In 1970 researchers led by Albert Ghiorso at the Berkeley Laboratory of the University of California by bombardment of californium with nitrogen ions and named Hahnium. Also this element was named Nielsbohrium.

Element Samarium, Sm, Lanthanide. Samarium is one of the less common of the rare earth elements, being on the one hand much less abundant than the other elements of the cerium group, and on the other hand much more abundant than europium, terbium, and thulium. It is about as plentiful as gadolinium. Samarium is a yellow metal of density 7. The metal quickly tarnishes in the air. Extracted by Mosander from ceria earth. The samarskite mineral was named.

Element Tantalum, Ta, Transition Metal. The discovery of transition metal tantalum. Symbolizing oxide is insoluble in acid, and was unable, just as the mythological Tantalos. Ekeberg called the ores in which tantalum. Was discovered tantalite and yttrotantalite. Perhaps Ekeberg isolated impure tantalum. Deep layers and upper mantle are poor by tantalum.

Element Hafnium, Hf, Transition Metal. In 1911 Urbain noticed several new lines in spectrum of the fractions of yttria mother solution and, thinking he had found a new element similar to the rare earths, called it celtium.

Element Lanthanum, La, Lanthanide. Lanthanum is a tin-white metal of density 6. It is malleable, but not ductile. Measurements made with material of doubtful purity indicate that lanthanum is feebly paramagnetic, but this is questionable. 923 and its heat of formation 97. it resembles the corresponding cerium compound.