Introduction to Tin
The element Tin, located in Group 14 on the Periodic Table, falls into the post-transition metal category. We typically encounter this metal mixed, or alloyed, with other metals; however, it is relatively non-reactive at room temperatures. Tin is a malleable, silvery substance that gives off a slightly bluish tinge.
Ten Amazing Facts About Tin
1. When you bend a bar of tin, it emits a screaming sound called a “tin cry.” This phenomenon results from the breakage of crystal lattice structures within the substance.
2. The usage of tin dates back to ancient civilizations.
3. When craftsmen struggled to work with soft tin, they formed bronze by alloying tin with copper.
4. Tin possesses more isotopes than any other element.
5. The United States consumes more tin than any other country in the world.
6. Scholars derived the elemental symbol for tin, Sn, from the Latin term “stannum,” an alloy of lead and silver.
7. Scientists first observed the Meissner Effect, typically seen in superconductor substances, in tin crystals.
8. TIn is one of the easiest metals to melt, which means it can easily be cast into different shapes and figures, like tin soldiers.
9. Making tin crystals is one of the coolest chemistry experiments you can do.
10. Tin changing from the beta to the alpha allotrope in cold weather is often blamed for causing Robert Scott’s Antarctica expedition to fail.
Allotropes of Tin
Tin exists in two different forms, or allotropes: white (beta) and gray (alpha). While metallic β-tin remains malleable and stable at room temperature, nonmetallic α-tin appears brittle.
Scientists can generate white tin, the more familiar and common form, from gray tin. This process occurs rapidly at temperatures exceeding 100°C. They can also transition white tin back to gray tin at lower temperatures of -50°C in a process known as “tin pest.” However, trace amounts of antimony, bismuth, copper, lead, silver, or gold, typically present in commercial tin, hinder this reaction.
In regard to structural differences, white tin adopts a tetragonal crystalline shape, while gray tin appears cubic.
Tin pest can occur spontaneously under severely cold conditions. Robert Scott’s expedition to Antarctica provides an example of such a scenario. Although Scott and his research team meticulously prepared for their journey to the South Pole, they did not anticipate the effects of the region’s cold climate on their tin-containing possessions. Scientists postulate that everything from the buttons on their jackets to their tin can food containers changed from white tin to gray tin. The gray allotrope of tin, as discussed, is brittle and powder-like. Because of this shift, Scott’s men likely had a much more difficult time staying warm and fed—this led to their ultimate demise and the failure of their mission.
Tin in the Environment
Tin only composes about 2ppm of the Earth’s crust, rendering the element relatively rare in comparison to other more abundant metals.
Where is tin found?
The element tin typically appears in certain countries, including Bolivia, Indonesia, Thailand, and Nigeria. Little tin can be found in the United States; the vast majority of this tin comes from Alaska.
The majority of sourced tin comes from different ores, which scientists obtain from mines and natural deposits. The most popular ore that contains tin is known as Cassiterite (SnO2), from which researchers generate tin by reducing it with carbon in a hot furnace. Tin is also found in the mineral Stannite, which is a sulfide of tin, iron and copper.
History of Tin
We can trace the origins of tin back to the prehistoric Bronze Age period, which spanned from 3300 BCE to 1200 BCE. During this time, people used tin to make bronze, an alloy of tin (12%) and copper.
Who discovered tin?
Tin has been around for a long time, so we don’t know who discovered it. Citizens of Ur, a city-state in ancient Mesopotamia, were likely the first people to encounter the element. This dramatically altered civilization, marking the beginning of our interaction with different metals and associated usage of weapons.
Tin mining peaked between the 8th Century BCE and the 6th Century AD, specifically in England and Spain. This prompted the domination of tin trade in the Mediterranean Sea.
Later on, in 1673, British scientist Robert Boyle performed experiments on the pure element tin. He published some descriptions of the oxidation of tin using different materials, fueling the increase in tin-related scientific literature and experimental studies.
In 1795, Napoleon offered a monetary prize to anyone who could develop an effective food-preserving method for the French military forces. This led to the creation and implementation of tin cans, which people used to conserve all types of food, including meats, vegetables, fruits, and condiments. However, these cans often contributed to lead poisoning, since their production involved smoldering tin-lead alloys together.
The United States began stockpiling for wartime purposes following World War II in 1945. Tin soon became a major component of this stockpiling effort; currently, tin contributes the most value among the non-fuel minerals in the stockpile.
In 1901, the United States founded the American Can Company; this company generated over 90% of tin cans used in the country. But due in large part to health risks related to lead poisoning, tin cans currently in use do not actually contain any tin. Because of the element’s relative scarcity, modern cans are typically composed of aluminium, steel, and other similar metals.
Tin Chemistry: Reactions, Compounds, Oxidation States, and Synthesis
Tin – Chemical Properties & Reactions
Tin does not react quickly with water or air, but it is readily attacked by both strong acids and strong bases. Tin forms a protective oxide layer that resists further oxidation in air.
Tin + Air
This metal does not react with air under normal conditions. However, tin reacts with oxygen in the presence of heat to form tin oxide.
Sn(s) + O2(g) → SnO2(s)
Tin + Halogens
Tin reacts with halides to form compounds; here, tin reacts with chlorine to form tin(IV) chloride.
Sn(s) + 2 Cl2(g) → SnCl4(s)
Tin + Acid
Although tin will not typically react with weak acids, strong acids can prompt chemical reactions. In this example, strong acid HCl combines with tin to form tin(II) chloride and hydrogen. The reaction is slow, and heating the solution is recommended to help it proceed more quickly. Tin (II) chloride is sometimes used as a reducing agent.
Sn(s) + HCl → SnCl2(s) + H2(g)
The reaction with nitric acid will depend on the temperature and concentration. Dilute nitric acid will produce ammonium nitrate and tin (II) nitrate, while more concentrated acid will produce tin (IV) oxide, SnO2, or stannic acid, H2SnO3 along with toxic nitrogen dioxide.
In aqua regia, tin reacts quickly and is oxidized to tin (IV) chloride.
4HCl + 2HNO3 + Sn -> NO2 + NO + SnCl4 + 3H2O
Tin + Water
Similar to air, tin does not react with water under normal conditions. However, when exposed to steam, the element reacts to form tin dioxide and hydrogen.
Sn(s) + 2 H2O(g) → SnO2(s) + 2 H2(g)
Tin has quite an interesting chemistry because it can exist in 2 different oxidation states, and the tin (II) ion acts as a reducing agent. Also, some tin (IV) compounds like tin (IV) iodide and tin(IV) sulfide can be very colorful.
The main source of tin derives from the mineral form of Tin(IV) oxide: SnO₂, or stannic oxide. Under normal conditions, this ore appears colorless and solid. This compound utilizes tin in its +4 oxidation state.
Tin(II) oxide: SnO, or stannous oxide, represents the other form of this compound. It utilizes tin in its +2 oxidation state.
Tin(II) bromide: SnBr2, Tin(II) chloride: SnCl2, Tin(II) fluoride: SnF2, and Tin(II) iodide: SnI2 contain tin in its +2 oxidation state.
Tin(IV) bromide: SnBr4, Tin(IV) chloride: SnCl4, Tin(IV) fluoride: SnF4, and Tin(IV) iodide: SnI4 contain tin in its +4 oxidation state.
Synthesis of Tin (IV) Iodide
Tin (IV) iodide is a beautiful reddish-orange covalent compound. It can be formed by heating tin with 3 to 4 times it’s weight of iodine in a organic solvent like dichloromethane or chloroform. Best results are when a reflux condenser is used. Cooling the solution will result in SnI4 precipitating out. Tin (IV) iodide reacts with water slowly to form tin dioxide and hydroiodic acid, HI. It can also form the SnI6-2 ion, hexaiodostannate ion, with cesium and rubidium.
Tin forms a hydroxide compound called Tin(II) hydroxide: Sn(OH)2. This molecule contains an octahedron of Sn atoms, each “capped” by oxide or hydroxide compounds.
White tin compounds precipitate out of solutions in the presence of hydroxide ions. In this example, such ions prompt the precipitation of Tin(II).
Sn2+(aq) + 2 OH−(aq) → Sn(OH)2(s) [white]
Tin Oxidation States
Tin exists in two oxidation states: +2 and +4. Elemental tin readily oxidizes to the 2+ ion in acidic solution; this compound can also convert to the +4 ion when mixed with mild oxidizing agents.
Isolation of Tin
Pure tin is easy to make, by simply placing a more reactive metal like zinc into a solution of tin (II) chloride.
Scientists also smelt tin with carbon at temperatures exceeding 1370°C. This produces low purity tin and carbon dioxide; they can then refine this tin to a higher purity through methods such as boiling and liquation.
Tin’s Applications to Today’s World
What is tin used for?
Tin’s malleability, resistance to corrosion, and anti-reactivity make it an extremely useful element. This metal frequently functions as a protective polish, or coating, on other metals to inhibit corrosion on their surfaces.
Alloys of tin, as discussed, also have relevant applications. For example, the combination of tin and lead produces pewter and solder, which are utilized in electronic, mechanical, and even art-related industries. Pewter consists of 91% tin, 7.5% antimony and 1.5% copper. Various superconductive wires and magnets also contain an alloy, comprised of tin and niobium. And of course, bronze is a very common tin alloy – used historically to make weapons.
Researchers have also found tin useful in the production of window glass, called the Pilkington process. During this process, molten glass combines with molten tin. When the glass floats to the top of the mixture, it cools and forms flat, solid glass.
Different food-container companies also still use tin to plate their products. Although most “tin cans” no longer contain traces of this element, tin remains a component of many baking sheets, storage containers, and skillets.
Physical Properties of Tin
- Symbol: Sn
- Melting point: 505.09 K; 231.90 °C; 449.50 °F
- Boiling point: 2875.00 K; 2602.00 °C; 4716.00 °F
- Density: 7.30 g/cm^3
- Atomic weight: 118.70
- Atomic number: 50
- Electronegativity: 1.96
- Classification: metal
- Natural abundance of X% in the earth’s crust: 0.00023%
- Electron shell configuration: [Kr] 4d10.
- Isotopes: Tin has ten stable isotopes: Sn-112, 114, 115, 116, 117, 118, 119, 120, 122, and 124
- This amount of isotopes is the largest of any element
- The most abundant isotopes among these include Sn-116, 118, and 120
- Found: most tin comes from different ores obtained from mines and natural deposits. The most popular tin-containing ore is Cassiterite (SnO2).
- Toxicity: no forms of tin are toxic; however large amounts of ingested inorganic tin can result in stomach, liver, and kidney issues
Where Can I Buy Tin?
You can purchase tin in either block or sheet form from many different vendors, including Amazon, Walmart, Lowe’s, and the Home Depot. Products containing tin, such as those covered in this article, are also widely available across the internet.