Tungsten is a metal known for its physical properties, making it one of the most robust elements on the periodic table. Designated by the chemical symbol W, which derives from its older name, wolfram, the element was first isolated in 1783 by Spanish chemists. Its name comes from the Swedish words tung sten, meaning “heavy stone,” a fitting description for its density.
Tungsten holds the distinction of having the highest melting point of all pure elements, at approximately 3,422°C. This property initially drove its use in early incandescent light bulb filaments. The combination of high melting point and high density establishes tungsten as a material of choice for high-performance applications.
Calculating the Mass of a Cubic Meter
The density of pure tungsten is measured at approximately 19.3 grams per cubic centimeter (\(\text{g/cm}^3\)). Converting this measurement, one cubic meter (\(\text{m}^3\)) of tungsten has a mass of approximately 19,300 kilograms (kg). To visualize this, a cube of tungsten measuring one meter on each side would hold the mass of several mid-sized cars.
The Atomic Reason for Density
Tungsten’s density results from a two-part atomic structure: the mass of its individual atoms and the efficiency of their packing arrangement. With an atomic number of 74 and an atomic mass of 183.84, the tungsten atom contains a high number of protons and neutrons, making each atom massive. These heavy atoms are arranged in a compact body-centered cubic (BCC) crystal lattice structure, which minimizes the empty space between atoms. The close proximity and large mass of the atoms contribute to the overall bulk density.
A factor in this density is the influence of relativistic effects on the element’s electrons. Because tungsten is a heavy element, its inner-shell electrons move at speeds high enough for Einstein’s theory of relativity to affect their behavior. This causes the inner s-orbitals to contract closer to the nucleus, which influences the outer electron shells and contributes to the compact atomic radius. This tight packing of massive atoms is the scientific reason tungsten achieves its high density.
Practical Comparisons to Common Materials
To grasp the scale of tungsten’s density, it helps to compare its mass to familiar materials in the same volume. A cubic meter of water, for instance, has a mass of 1,000 kg, meaning tungsten is over 19 times heavier than water. The difference is apparent when comparing it to common construction metals, as a cubic meter of typical steel has a mass of about 7,850 to 8,050 kg.
Tungsten’s mass is more than double that of steel for the same volume. Even lead, commonly associated with being a heavy metal, is significantly less dense than tungsten, weighing approximately 11,340 kg per cubic meter. This means a tungsten object will have a mass nearly 70% greater than an identically sized lead object, making tungsten the preferred choice when maximum mass must be contained within minimum volume.
Applications Where High Density Is Essential
The utility of tungsten’s high mass-per-volume ratio is seen across numerous industries. A common application is in counterweights and ballast for balancing and vibration dampening. High-density tungsten alloys are used in aircraft control surfaces, race car weights, and rotating assemblies like crankshafts and turbine rotors, where precise and compact mass distribution is necessary. The small volume required to achieve a large mass allows engineers to design smaller components while retaining the necessary inertia or balance.
In the defense sector, the high density of tungsten is utilized in kinetic energy penetrators, which are armor-piercing projectiles. The concentration of mass in a small diameter gives the projectile high momentum and superior penetration capability upon impact. Tungsten’s density is also a desirable property for radiation shielding, particularly against high-energy X-rays and gamma rays. Its dense atomic structure effectively absorbs radiation, making it an excellent, non-toxic alternative to lead shielding in medical and nuclear environments.