What Is Molybdenum?
Molybdenum is a chemical element with the symbol Mo and atomic number 42, found within the transition metal block of the periodic table.
A silvery metal with one of the highest melting points. Essential micronutrient for plants.
As a transition metal in Period 5 and Group 6 (Transition Metals), molybdenum's placement on the table reflects its electron configuration of [Kr] 4d⁵ 5s¹, which governs its bonding behavior and the type of compounds it typically forms.
Position on the Periodic Table
Molybdenum is located in Period 5, which continues the transition metal pattern seen in Period 4 but one principal shell further out.
Within that row, molybdenum sits in Group 6 (Transition Metals), alongside elements that share a similar number of valence electrons and, by extension, similar chemical behavior.
This position is not arbitrary — the periodic table was deliberately organized so that an element's row and column reveal its expected reactivity, bonding pattern, and physical state at a glance.
Physical & Chemical Properties
Molybdenum has an atomic mass of 95.960 u and a density of 10.22 g/cm³. Its melting point is 2623°C and its boiling point is 4639°C.
As a transition metal, molybdenum conducts electricity and heat well, and its atoms pack into a metallic crystal lattice held together by shared, delocalized electrons.
Electron Configuration Explained
Molybdenum's electron configuration is [Kr] 4d⁵ 5s¹, describing how its electrons are distributed across shells and subshells around the nucleus.
Reading the configuration in order shows electrons filling shells of increasing energy, following the standard Aufbau principle that explains how atomic structure builds up across the periodic table.
The outermost (valence) electrons shown in this configuration are what ultimately determine molybdenum's chemical reactivity and the type of bonds it forms with other elements.
History & Discovery
Molybdenum was formally discovered in 1778, C.W. Scheele, identified through the careful isolation and analytical techniques typical of that era's chemical research.
Many elements from this period were anticipated by Dmitri Mendeleev's periodic table, which successfully predicted gaps corresponding to undiscovered elements well before laboratory instruments existed to confirm them directly.
What Is Molybdenum Used For?
Molybdenum's specific properties make it useful in several applications, including:
- High-strength alloys
- Lubricants
- Catalysts
- Fertilizers
- Electrodes
These uses reflect molybdenum's underlying classification as a transition metal, since the same properties that define its category in chemistry also determine where it becomes practically useful.
Fun Facts About Molybdenum
- Molybdenum has one of the highest melting points (2623°C) — used in rocket nozzles.
- Molybdenum is element number 42 on the periodic table, in Period 5 and Group 6.
- Its standard atomic mass is 95.960 u, calculated from the natural abundance of its isotopes.
Frequently Asked Questions
What is Molybdenum's atomic number?
Molybdenum has atomic number 42.
What is Molybdenum's chemical symbol?
Molybdenum's symbol is Mo.
What group and period is Molybdenum in?
Molybdenum is in Period 5, Group 6 (Transition Metals).
What is Molybdenum's atomic mass?
Molybdenum's standard atomic mass is 95.960 u.