The question of whether bismuth is heavier than tungsten depends on the context, but a piece of tungsten is significantly heavier than a piece of bismuth of the same size. Tungsten (W, atomic number 74) is one of the densest naturally occurring elements. Bismuth (Bi, element 83) is a post-transition metal known for its unique properties. Both are metals, but their physical properties diverge dramatically, leading to distinct roles in science and industry.
Defining ‘Heaviness’: Atomic Mass Versus Density
The definition of “heavier” depends on whether one considers a single atom or a bulk quantity of the material. At the atomic level, bismuth is the heavier element, with an atomic weight of approximately 208.98, compared to tungsten’s 183.84. This is expected since bismuth (83) has a higher atomic number than tungsten (74), meaning a bismuth atom contains more protons and neutrons.
In practical terms, “heaviness” refers to density, which measures how tightly atoms are packed together in a given volume. Pure tungsten has an extremely high density of about 19.25 grams per cubic centimeter (g/cm³). Bismuth, by contrast, has a density of only about 9.78 g/cm³, making it almost twice as light as tungsten for the same volume. This difference is due to their crystal structures; tungsten’s body-centered cubic lattice allows for a much more compact arrangement than the less tightly packed rhombohedral structure of bismuth.
Tungsten: The Applications of Extreme Density
Tungsten’s remarkable bulk density is a defining characteristic, comparable to gold and uranium. This density is coupled with the highest melting point of any metal at 3,422°C. This combination of properties makes it invaluable for applications requiring extreme durability and mass concentration. Its density is harnessed in mass-balancing applications, such as counterweights in aircraft and high-performance engines where maximum weight is needed in limited space.
The metal is also exceptionally hard (Mohs hardness of 7.5), utilized in the production of tungsten carbide. Tungsten carbide is one of the hardest compounds known, making it the material of choice for industrial cutting tools, mining drill bits, and armor-piercing ammunition. The high density of tungsten makes it an effective material for radiation shielding, absorbing X-rays and gamma rays.
Bismuth: The Low-Toxicity Alternative
Bismuth is chiefly valued for a unique set of properties, particularly its relatively low toxicity. Pure bismuth is one of the few elements that expands upon solidification, a rare trait useful in casting applications for sharp impressions. It also has an unusually low melting point of 271°C, allowing its use in fusible alloys for thermal fuses and fire safety devices.
Bismuth has emerged as the primary non-toxic replacement for lead in numerous consumer and industrial applications. Concerns over lead toxicity have driven a shift to bismuth-based alloys for plumbing fixtures, fishing weights, and hunting shot. The low toxicity of bismuth also allows its compounds to be used directly in pharmaceuticals, such as stomach-soothing medications, and in pearlescent pigments for cosmetics.