An Element of Interest...

Pure molybdenum is soft and ductile (able to be stretched). Molybdenite (MoS₂) is most common molybdenum ore with physical properties that are nearly the same as those that are exhibited by graphite except that it leaves a green streak on paper. Molybdenum is able to use the one electron in its 5s and five electrons in its 4d shells as valence electrons thus giving it a unique flexibility in valencies and has been observed to have valencies of 0, 2+, 3+, 4+, 5+, and 6+.

Life

Molybdenum is the least needed of elements required by living tissue. Although the importance of Molybdenum to the human body is uncertain, a balance must be maintained between the amount of it and copper. In other words, molybdenum toxicity and copper deficiency cause the same symptoms. Molybdenum is found in legumes (fruits, seeds, or any plant used as food) and becomes more highly concentrated in animals higher up the food chain. Excessive amounts in cattle causes teart, a cholera like disorder. In humans, however, over exposure is rare regardless of the diet.

Practical Applications

Impure molybdenum is extremely hard and has a high heat resistance with a melting point of 870K. Combined with iron some its hardness and heat resistance is imbued making it useful for cutting forging tools. Zinc molybdate is the pigment found in white paints used on sea faring vessels because it is nontoxic.

Element Profile Source: The Camelot Chemistry Primer. Coop, Dwight Wayne. Kenndon, Krastins & Gould, Publishers. 1992
Photographic Source: Time Life Books: Life Science Library: A Periodic Table of the Elements