Molybdenum: Hard to spell, essential for life

Kelly Resmer
12 March 2015

Name: Molybdenum

Symbol: Mo
Atomic Number: 42
Relative Atomic Mass: 95.96
Category: Transition metal (Group 6)
Appearance: Silver coloured metal

Above: Image © istockphoto.com/3dalia

Perhaps you've never heard of molybdenum, but you couldn’t live without it! Because of its high melting point, the element is mined around the world for industrial applications such as strengthening steel. But molybdenum is also vital to the survival of plants and animals because of how it helps carry out chemical reactions within a wide variety of organisms.

Although molybdenum is toxic to humans in large quantities, it is essential for many biological processes that happen inside your body. These include producing energy in cells, processing waste, and sending signals through the nervous system. You ingest small amounts of molybdenum from foods such as beans, peas, lentils, grains, leafy vegetables, liver, and nuts.

Did you know? Molecules like enzymes that speed up chemical reactions are called catalysts.

In living things, molybdenum is used by dozens of different enzymes—biological molecules that are usually made of proteins—to speed up chemical reactions. For example, without enzymes, it could take years for your body to digest a meal! Molybdenum acts as a cofactor: a substance needed by an enzyme to carry out a particular reaction. Since they help to activate enzymes, cofactors are commonly called “helper molecules”.

These helper molecules are essential for good health. For example, molybdenum cofactor deficiency is a genetic condition that prevents the body from using the molybdenum cofactor. As a result, people with the conditions develop symptoms such as difficulty eating, uncontrollable seizures, and damaged brain tissue. Most children born with the condition do not live more than a few years.

In some organisms, molybdenum is a cofactor for the enzyme nitrogenase, which speeds up the conversion of nitrogen gas (N2) found in the air to ammonia (NH3).

Did you know? About 50 different enzymes that catalyze essential biological processes contain molybdenum.

Plants use the ammonia produced in this way to maintain themselves and grow. Laboratory experiments have shown that converting nitrogen gas to ammonia without the help of enzymes would require very high temperatures (300 °C) and pressures (20,000 kPa). In other words, many plants could simply not survive without nitrogenase and molybdenum.

In fact, without molybdenum, a wide range of organisms—including bacteria, plants, animals, and human beings—would die. Not bad for an element that you only consume in very small amounts and you might never have heard of before!

Learn more!

General information about the element, including its uses, properties and history.

Molybdenum (2015)
UK Royal Society of Chemistry

Website with information on Molybdenum maintained by a trade association representing molybdenum producers, consumers, converters, traders and assayers.


Reflections by a chemist on the importance of melybdenum for both life and industry.

Made by molybdenum (2014)
Anders Lennartson, Nature Chemistry 6

General information on the condition, with links to additional resources.

Made by molybdenum (2014)
Genetics Home Reference, US National Library of Medicine

Kelly Resmer

Kelly is a chemistry undergraduate laboratory instructor in Halifax.  She loves working with students in the lab, watching chemistry happen! She has a PhD in chemistry and is very interested in studying and learning about bacteria, the good and the bad ones! 


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