Tin (Sn)

Tin is a chemical element with the atomic number 50 in the periodic table. It’s the 49th most plentiful element found in Earth’s crust. Being a member of the post-transition metal family of periodic, the element 50 has four valence electrons and three allotropes. 

While the pure, elemental form of tin is classified as a non-toxic substance, the numerous organotin compounds (hydrides), and inorganic compounds (such as tin tetraiodide, tin tetrabromide) may be extremely toxic. 

Chemical and Physical Properties of Tin

Atomic number50
Period5 (p-block)
ColorA silvery-gray metal
Physical stateSolid at 20°C
Half-lifeFrom 5 milliseconds to 230,000 years
Density7.30 g/cm³
Melting point231.928°C, 449.47°F, 505.078 K
Boiling point2586°C, 4687°F, 2859 K
Van der Waals radius0.162 nm
Ionic radius0.71 nm (+4)
Atomic weight118.71 g.mol-1
Most characteristic isotope120Sn
Electronic shell[Kr] 4d10 5s2 5p2
The energy of the first ionization708.4 kJ.mol-1
The energy of the second ionization1411.4 kJ.mol-1
The energy of the third ionization2942.2 kJ.mol-1
The energy of the fourth ionization3929.3 kJ.mol-1
Crystal StructureTetragonal
Covalent Radius1.41 Å
Atomic Radius1.72 Å
Atomic Volume16.3 cm³/mol
Name OriginNamed after Etruscan god, Tinia
DiscovererKnown to the ancients
Oxydation States(4),2
UsesUsed in steel cans, solder, bronze, pewter, and toothpaste
DescriptionHard, brittle, silvery-white semimetal

With the periodic table symbol Sn, atomic number 50, atomic mass of 118.69 g.mol-1, and electron configuration [Kr] 4d105s25p2, tin is a soft, pliable, and easily malleable silvery-white metal. It reaches its boiling point at 2586°C, 4687°F, 2859 K, while the melting point is achieved at 231.928°C, 449.47°F, 505.078 K. This member of the post-transition metals family of elements has an electronegativity of 1.8 according to Pauling, whereas the atomic radius according to van der Waals is 0.162 nm. Tin displays strong anti-corrosive properties, even when it’s exposed to seawater, distilled, or tap water.

There are two basic allotropes of tin metal: white tin (Sn)  and gray tin (Sn). While white tin is the form of element 50 which is widely used in everyday life, the gray form is a non-metallic allomorph of this chemical that occurs in a form of a powder. 

When molten tin cools down, the third allotrope of this element forms in rhombic crystals. This brittle form of tin is conveniently labeled as rhombic tin (Sn). This transition of the pure, elemental form of tin occurs when this chemical is exposed to a temperature below 13.2oC. “Tin pest” refers to the reverse transformation that occurs rapidly at low temperatures. It can be prevented by small amounts of copper, lead, antimony, bismuth, silver, or gold, which naturally occur in the commercially produced tin.

How Was Tin Discovered?

The discovery story of element 50 originates from ancient times. For this reason, the world of science lacks information on who was the discoverer of tin. 

Archaeological researches provide evidence for the so-called ‘tin route’ stretching over the Balkan peninsula (mostly Greece and Turkey) and Israel. However, ancient Greeks seem to have had another source for tin, located in Great Britain and Spain. They have referred to these locations rich in tin ores as ‘The Cassiterides’. During the Bronze Age, tin was used as a part of bronze. Added to bronze, tin would add hardness to copper. 

How Did Tin Get Its Name?

The name of this element is derived from the Anglo-Saxon word ‘tin‘, with an unknown meaning. The symbol Sn for the element 50 presents an abbreviation of the Latin word for the element tin, ‘stannum’, that originates from the Indo-European term for ‘dripping’. 

Where Can You Find Tin?

There’s about 0.001 percent of tin in Earth‘s crust. In the Universe, element 50 occurs as a product of neutron absorption. Since tin ore is resistant to weathering and the tin oxide (SnO2) is insoluble, there is low absorption of element 50 in both soil and waters. 

Naturally occurring tin can be found in the ore labeled as cassiterite (tin(IV) oxide). This post-transition metal can be also extracted from a few other tin-containing minerals, such as teallite, cylindrite, tannite, canfieldite, and franckeite. 

For commercial purposes, tin is mainly obtained by reducing the ore with coal in a furnace.  It’s smelted at temperatures of up to 2500°F (1370°C) with carbon. This chemical reaction produces low purity tin and CO2 gas. After this step, tin is further refined to a tin metal of high purity (>99%) by boiling, electrolysis, or liquidation. 

The world’s largest tin mines are located in China, Peru, Bolivia, Indonesia, Thailand, and Malaysia. These countries form the ‘tin belt’ of locations where tin ores are naturally found. Small amounts of tin have also been found in the United States, mainly in Alaska and California.

Tin in Everyday Life

Tin (Sn) is one of the most versatile chemical elements that can be used in numerous instances of everyday life:

  • Tin alloys are commonly used for plating steel cans used for packaging and storing food. This method of storing food was first patented in 1839 by the English merchant Peter Durand. Tin cans are typically made from tin-coated steel. In addition, such tin plate is also applied in electric circuits, babbitt metal, dental amalgams, pewter, and bell metal;
  • Tin foil is a commonly used everyday product made of tin for the preservation and storing of food;
  • Some toothpaste and mouthwashes contain stannous fluoride (SnF2);
  • The coils of superconducting magnets are commonly made of niobium-tin compound (Nb3Sn);
  • The toxic organic tin compounds are widely used as fungicides and biocides; stabilizers for polyvinyl chloride, and fire retardants;
  • Tin or lead soft solders typically consist of more than 60% tin;
  • Tin(II) chloride is one of the most important tin compounds. This tin salt is used both as a mordant for dyeing calico and silk and as a reducing agent;
  • Element 50 is commonly used in the manufacturing process of bronze and pewter;
  • Zinc stannate (Zn2SnO4) is a fire-retardant that is used in plastics;
  • Phones and electronics are comprised of lightweight parts made with tin, which is also a great electricity conductor;
  • Floating molten glass on molten tin is used in the manufacturing process of window glass to produce a flat and smooth surface.

How Dangerous Is Tin?

Tin metal is classified as a nontoxic substance. However, the compounds of this chemical element can be highly toxic. Even more, the organic compounds of tin are more dangerous for humans than the non-organic tin compounds. They may cause adverse health effects experienced as: 

  • Sickness; 
  • Dizziness; 
  • Headaches; 
  • Loss of breath; 
  • Liver damage;
  • Sleeping disorders;
  • Damage of the cell membranes.

While there are no known biological roles of tin in humans, some of the organic tin compounds are highly toxic for marine life when used as anti-fouling paint for boats and ships. Plants can also easily absorb tin. For this reason, the use of tin compounds in paint and polishes has been banned in many countries. 

Environmental Effects of Tin

Widely used in industries, tin particles and dust can be released into the air as pollutants. Tin mining is one of the greatest environmental concerns of our time. 

An investigation conducted by ‘Business Week’ points to the deadly effects of tin mining in Indonesia. Working without proper safety equipment, the miners’ lives are endangered not only by the frequent structural collapses but also by the prolonged exposure to this metal. Also, the byproducts and waste of tin mining severely increase environmental pollution. 

Isotopes of Tin

Tin (50Sn) has 40 isotopes with atomic mass ranging from tin-99 to tin-139. This chemical element has ten stable isotopes, which is the largest number of isotopes detected in any chemical element. This is likely a result of tin’s ‘magic number’ of protons that identify the stability of this post-transition metal. 

Having a half-life of 230,000 years, the 126Sn is the longest living radioisotope of tin, while the average half-life of the other tin radioisotopes is less than a year. The most abundant form of element 50 is the tin-120 isotope. 

Main Isotopes of Tin
Iso­tope Decay
  abun­dance half-life (t1/2) mode pro­duct  
112Sn 0.97% stable
114Sn 0.66% stable
115Sn 0.34% stable
116Sn 14.54% stable
117Sn 7.68% stable
118Sn 24.22% stable
119Sn 8.59% stable
120Sn 32.58% stable
122Sn 4.63% stable
124Sn 5.79% stable
126Sn trace 2.3×105 y β 126Sb  

Source: Wikipedia

List of Tin Compounds 

Tin (Sn) has a diamond cubic structure and usually occurs in the oxidation state 0 (zero) when it becomes a part of a compound. However, it can also occur in +2 and +4 oxidation states, as “stannous” tin (II) and “stannic” tin (IV). This pliable substance readily reacts with acid salts, alkalis, and strong acids.

While the term stannic acid Sn(OH)4 refers to any acid that occurs in a form of an amorphous powder and possesses properties of a stannic oxide (SnO2) hydrate, stannates are any of the tin (Sn) compounds. We can distinguish two types of tin oxyanions: orthostannates and metastannates. The stannates (both orthostannates and metastannates) display semiconducting properties.  

The following is a list of the most commonly occurring tin compounds:

  • Asbecasite
  • Mosaic gold
  • Stannane
  • Tin(IV) oxide
  • Tin selenide
  • Tin telluride
  • Tin(II) 2-ethylhexanoate
  • Tin(II) bromide
  • Tin(II) chloride
  • Tin(II) fluoride
  • Tin(II) hydroxide
  • Tin(II) iodide
  • Tin(II) oxide
  • Tin(II) sulfate
  • Tin(II) sulfide
  • Tin(IV) bromide
  • Tin(IV) chloride
  • Tin(IV) fluoride
  • Tin(IV) iodide
  • Tin(IV) nitrate
  • Tin(IV) sulfide
  • Barium stannate
  • Sodium stannate
  • Organotin chemistry
  • Stannoxane
  • Butyltin trichloride
  • Dibutyltin dilaurate
  • Dibutyltin oxide
  • Hydrostannylation
  • Otera’s catalyst
  • Polystannane
  • Stannatrane
  • Stannocene
  • Stannylene
  • Stannabenzene
  • Stannole
  • Tetrabutyltin
  • Tetraethyltin
  • Tetramethyltin
  • Tributyltin
  • Tributyltin azide
  • Tributyltin chloride
  • Tributyltin hydride
  • Tributyltin oxide
  • Trimethyltin chloride
  • Triphenyltin compounds
  • Vinyl tributyltin

5 Interesting Facts and Explanations

  1. When the tin metal undergoes a bending procedure, it produces a characteristic sound that is labeled as ‘the tin cry’. It occurs as a result of the breaking of tin’s crystalline structure.
  2. Metastannates are salts of the metastannic acid (H2O3Sn). This acid is a tin compound that occurs as a result of the isomeric modification of stannic acid.
  3. Bronze is usually made of 10% tin and 90% copper.
  4. Babbitt metal (also: bearing metal) is a tin-based low-friction metal alloy used as a bearing material for axles and crankshafts. It was invented by the American inventor Isaac Babbitt (1799 – 1862) in 1893.  Nowadays, babbitt metal is commonly used in engine bearings and solders.
  5. The mineral cassiterite typically contains about 80% tin.