Tin Facts – Sn or Atomic Number 50


Tin Facts

Tin is a chemical element with the symbol Sn and atomic number 50. It is a post-transition metal in group 14 of the periodic table. Tin is a soft metal that is malleable, ductile, and corrosion-resistant, making it useful in alloys and coatings.

Discovery, Naming, and Isolation

Tin has been known since ancient times. The earliest recorded use of tin traces back to the Bronze Age, as it is a key component in bronze alloys. The element’s name comes from the Anglo-Saxon word “tin” and the symbol Sn comes from the Latin word “stannum” or the Cornish word “stean”. Cornwall was an early source of tin ore. The process of isolating tin from its ores, primarily cassiterite (SnO2), likely began around 3,000 BC.

Appearance and Properties

Tin is a silvery-white metal that is soft enough that it’s easily cut or bent. When a bar of tin is bent, it emits a characteristic crackling sound known as the “tin cry,” caused by the breaking of tin’s twinned crystal structure. The metal has a relatively low melting point of 231.93°C, but a high boiling point of 2602°C.

Tin Allotropes

Tin exists in different crystalline forms or allotropes:

  1. White Tin (Beta Tin): This is the metallic form of tin, which is stable at and above room temperature. White tin is malleable, ductile, and the common form of tin used in various applications. It has a body-centered tetragonal crystal structure.
  2. Gray Tin (Alpha Tin): At temperatures below 13.2°C, white tin slowly turns into gray tin. Gray tin is brittle and has a diamond cubic structure. This transformation sometimes leads to a phenomenon known as “tin pest,” where the surface of tin objects disintegrates into a powder. However, the presence of small amounts of bismuth, antimony, lead, or silver help stabilize tin against tin pest.
  3. Rhombohedral Tin (Gamma Tin): This allotrope is stable at very high pressures. It is not typically encountered in everyday applications.

The transition between these allotropes has important implications in cold climates and for space applications, where temperatures changes potential cause structural failure of tin-containing components.

Element Group

As part of Group 14 in the periodic table, tin shares properties with other group elements like carbon, silicon, germanium, and lead. Another name for group 14 is the carbon group. Tin and other elements in the group have four electrons in their valence electron shell. These elements readily form covalent bonds with other elements.

Electron Levels of a Tin Atom

Natural and Radioactive Isotopes

Tin has ten stable isotopes, which is the largest number of stable isotopes of any element. These include Sn-112, Sn-114 to Sn-120, Sn-122, and Sn-124. Sn-120 is the most abundant isotope, comprising nearly a third of the natural element. There are also numerous unstable isotopes, with Sn-126 being the most important as a potential therapeutic agent in nuclear medicine.

The likely reason why tin has so many stable isotopes is because its atomic number of 50 gives it a “magic number” in nuclear physics. This means the nucleons in the atomic nucleus arrange into stable complete shells.

Abundance and Sources

Tin originates from the long s-process in stars and beta decay of heavy indium isotopes. The element is relatively rare, constituting about 2 ppm of the Earth’s crust. It is the 49th most abundant element. The main source of tin is cassiterite ore, which occurs in Malaysia, Indonesia, Thailand, Bolivia, and Nigeria. Tin occurs in compounds and minerals, and only rarely as a native pure element.

Purification

Tin primarily comes from the ore cassiterite using a smelting method. The process involves crushing the ore is crushed, concentrating the element using flotation, then smelting in a furnace to separate the tin from impurities.

Uses of Tin

Most people associate tin with cans, but it has a wide variety of uses:

  • Alloys: Tin’s most well-known use is in bronze, which is an alloy with copper. It’s also used in solder (for joining pipes and electronics), pewter, and bearing metals.
  • Tin Plating: A thin layer of tin applied to other metals helps prevent corrosion. This is crucial in making “tin cans” for food preservation, which are actually steel cans with a tin coating.
  • Organotin Compounds: These find use in PVC plastic stabilization, reducing degradation from heat and light. Organotins also serve as biocides in antifouling ship paints.
  • Lead-Acid Batteries: Some lead-acid batteries contain tin to improve the battery life and performance.
  • Glass Manufacturing: The float glass process involves pouring molten glass onto a surface of molten tin to produce flat panels of glass.
  • Culinary Uses: Certain grades of tin line copper cookware to prevent copper from contaminating food.
  • Dental Amalgams: Tin, in combination with silver and mercury, makes dental amalgams for filling cavities.
  • Chemical Catalysts: Certain tin compounds are catalysts in the production of polyurethane foam and other industrial processes.
  • Electronic Components: Tin finds use in various electronic components due to its conductive properties.
  • Window Glass Coatings: Transparent tin oxide coatings on window glass produce electrically conductive and heat-reflective surfaces.
  • Piezoelectric Devices: Tin oxide is a component of piezoelectric materials, which convert mechanical energy into electrical energy and vice versa.

Oxidation States

Tin displays all of the oxidation states from -4 to +4 (-4, -3, -2, -1, 0, +1, +2, +3, +4). The +2 and +4 oxidation states are the usual states, with +4 being the more stable and common form.

Biological Role, Health Effects, and Toxicity

Tin has no known biological role in any living organism. The metal, its salts, and its oxides exhibit low toxicity, partly because of the low absorption of this element. Canned food containing around 200 mg/kg of tin produces nausea, diarrhea, and vomiting. This toxicity relates mainly to the way tin interferes with copper and iron metabolism. Certain organotin compounds are about as toxic as cyanide and are regulated due to their environmental impact. Organotin compounds are highly toxic to plants, invertebrates, fungi, and bacteria, as well as humans and wildlife.

Key Tin Facts for Scientists

PropertyValue
NameTin
SymbolSn
Atomic Number50
Atomic Weight118.71
Group14
Period5
Blockp-block
Electron Configuration[Kr] 4d10 5s2 5p2
Number of Electrons/Shell2, 8, 18, 18, 4
State at Room TemperatureSolid
Melting Point231.93°C
Boiling Point2602°C
Density7.265 g/cm³ (white); 5.769 g/cm³ (gray)
Heat of Fusion7.03 kJ/mol (white)
Heat of Vaporization296.1 kJ/mol (white)
Molar Heat Capacity27.112 J/(mol·K) (white)
Oxidation States-4, -3,- 2, -1, 0, +1, +2, +3, +4 (main: +2, +4)
ElectronegativityPauling scale: 1.96
Ionization Energies1st: 708.6 kJ/mol
Atomic Radiusempirical: 140 pm
Covalent Radius139±4 pm
Van der Waals Radius217 pm
Crystal StructuresTetragonal (white), Diamond Cubic (gray)
Thermal Conductivity66.8 W/(m·K)
Electrical Resistivity115 nΩ·m
Young’s Modulus50 GPa
Shear Modulus18 GPa
Bulk Modulus58 GPa
Mohs Hardness1.5
Magnetic OrderingDiamagnetic (gray); Paramagnetic (white)

Interesting Tin Facts

  • Historical Significance: The discovery that mixing tin with copper produced bronze marked the transition from the Stone Age to the Bronze Age.
  • Tin Whiskers: In a peculiar phenomenon, tin spontaneously grows tiny, hair-like crystalline structures called “tin whiskers.” These whiskers cause electrical short circuits in electronics, posing significant challenges in the aerospace and electronics industries.
  • Symbol Origin: The symbol for tin, Sn, comes from its Latin name ‘stannum’. Interestingly, the word ‘stannum’ originally meant an alloy of silver and lead, and only later came to mean tin.
  • Tin’s Role in Organ Pipes: Tin is a key component in the construction of organ pipes. The amount of tin in the pipes affects the sound’s timbre, with higher tin content giving a brighter sound.
  • Geological Rarity: Despite its extensive use, tin is relatively rare, making up about 2 parts per million of the Earth’s crust, ranking it 49th in abundance.
  • Superconducting Properties: Under extremely low temperatures, tin becomes a superconductor, meaning it conducts electricity without resistance.
  • Role in Medieval Currency: In medieval times, particularly in England, tin was so valuable that tin blocks were a form of currency.
  • Tin in Literature and Myth: Tin is mentioned in various ancient texts, including the Bible. In Greek mythology, the god Dionysus was said to have turned a pirate ship into tin.
  • Recycling Efficiency: Tin is one of the most recyclable materials. Recycled tin meets a significant portion of the global demand.
  • Tin’s Impact on Art: Tin-based white paint was widely used by artists during the Renaissance because it provided a bright, opaque white color.
  • Astrological Metal: In astrology, tin is associated with the planet Jupiter, reflecting its historical importance and perceived nobility among metals.

References

  • Blunden, Steve; Wallace, Tony (2003). “Tin in canned food: a review and understanding of occurrence and effect”. Food and Chemical Toxicology. 41 (12): 1651–1662. doi:10.1016/S0278-6915(03)00217-5
  • Emsley, John (2011). Nature’s Building Blocks: An A-Z Guide to the Elements (New ed.). New York, United States: Oxford University Press. ISBN 978-0-19-960563-7.
  • Molodets, A.M.; Nabatov, S.S. (2000). “Thermodynamic potentials, diagram of state, and phase transitions of tin on shock compression”. High Temperature. 38 (5): 715–721. doi:10.1007/BF02755923
  • Walker, Phil (1994). “Doubly Magic Discovery of Tin-100”. Physics World. 7 (June): 28. doi:10.1088/2058-7058/7/6/24
  • Weast, Robert (1984). CRC, Handbook of Chemistry and Physics. Boca Raton, Florida: Chemical Rubber Company Publishing. ISBN 0-8493-0464-4.