Tin Facts

Tin Chemical & Physical Properties

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Tin Basic Facts

Atomic Number: 50

Symbol: Sn

Atomic Weight: 118.71

Discovery: Known since ancient time.

Electron Configuration: [Kr] 5s2 4d10 5p2

Word Origin: Anglo-Saxon tin, Latin stannum, both names for the element tin. Named after Etruscan god, Tinia; denoted by the Latin symbol for stannum.

Isotopes: Twenty-two isotopes of tin are known. Ordinary tin is composed of nine stable isotopes. Thirteen unstable isotopes have been recognized.

Properties: Tin has a melting point of 231.9681°C, boiling point of 2270°C, specific gravity (gray) of 5.75 or (white) 7.31, with a valence of 2 or 4. Tin is a malleable silvery-white metal which takes a high polish. It possesses a highly crystalline structure and is moderately ductile. When a bar of tin is bent, the crystals break, producing a characteristic 'tin cry'. Two or three allotropic forms of tin exist. Gray or a tin has a cubic structure. Upon warming, at 13.2°C gray tin changes to white or b tin, which has a tetragonal structure. This transition from the a to the b form is termed the tin pest. A g form may exist between 161°C and the melting point. When tin is cooled below 13.2°C, it slowly changes from the white form to the gray form, although the transition is affected by impurities such as zinc or aluminum and can be prevented if small amounts of bismuth or antimony are present. Tin is resistant to attack by sea, distilled, or soft tap water, but it will corrode in strong acids, alkalis, and acid salts.

The presence of oxygen in a solution accelerates the rate of corrosion.

Uses: Tin is used to coat other metals to prevent corrosion. Tin plate over steel is use to make cans for food. Some of the important alloys of tin are soft solder, fusible metal, type metal, bronze, pewter, Babbitt metal, bell metal, die casting alloy, White metal, and phosphor bronze. The chloride SnCl·H2O is used as a reducing agent and as a mordant for printing calico. Tin salts may be sprayed onto glass to produce electrically conductive coatings. Molten tin is used to float molten glass to produce window glass. Crystalline tin-niobium alloys are superconductive at very low temperatures.

Sources: The primary source of tin is cassiterite (SnO2). Tin is obtained by reducing its ore with coal in a reverberatory furnace.

Tin Physical Data

Element Classification: Metal

Density (g/cc): 7.31

Melting Point (K): 505.1

Boiling Point (K): 2543

Appearance: silvery-white, soft, malleable, ductile metal

Atomic Radius (pm): 162

Atomic Volume (cc/mol): 16.3

Covalent Radius (pm): 141

Ionic Radius: 71 (+4e) 93 (+2)

Specific Heat (@20°C J/g mol): 0.222

Fusion Heat (kJ/mol): 7.07

Evaporation Heat (kJ/mol): 296

Debye Temperature (K): 170.00

Pauling Negativity Number: 1.96

First Ionizing Energy (kJ/mol): 708.2

Lattice Structure: Tetragonal

Lattice Constant (Å): 5.820

References: Los Alamos National Laboratory (2001), Crescent Chemical Company (2001), Lange's Handbook of Chemistry (1952), CRC Handbook of Chemistry & Physics (18th Ed.)


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