Chemistry of Tin (Z=50)

Mentioned in the Hebrew scriptures, tin is of ancient origins. Tin is an element in Group 14 (the carbon family) and has mainly metallic properties. Tin has atomic number 50 and an atomic mass of 118.710 atomic mass units.

Introduction

Mentioned in the Hebrew scriptures, tin is of ancient origins. Early metal smiths were quick to learn that mixing copper with tin created a more durable metal (bronze), and it is principally for its alloys that tin is valued today. Named after the Etruscan god Tinia, the chemical symbol for tin is taken from the Latin stannum. The metal is silvery white and very soft when pure. It has the look of freshly cut aluminum, but the feel of lead.

Polished tin is slightly bluish. It has been used for many years in the coating of steel cans for food because it is more resistant to corrosion than iron. It forms a number of useful low-melting alloys (solders) which are used to connect electrical circuits. Bending a bar of tin produces a characteristic squealing sound called "tin cry". Tin shares chemical similarities with germanium and lead. Tin mining began in Australia in 1872, and today tin is used extensively in industry and commerce.

Table 1: Basic Properties of tin

Color	white with blueish tinge
Hardness	softer than gold, harder than lead
Atomic Radius	140 pm
Density	5.77g/cm^3
Melting Point	232 degrees Celsius
Boiling Point	2623 degrees Celsius
Electrical Conductivity	about 1/7th that of silver
Electrode Potential	>0.192V
First Ionization Energy	709 kJ/mol
Ionic Radius	93 pm

Reactions of Tin

Hydrogen	Tin not affected
Nitrogen	Tin absorbs it instead of hydrogen in electric discharge
Argon	No sign of a combination of tin with argon
Fluorine	Does not react with tin at low temperatures, but at 100 degrees Celsius they form stannic fluoride. Perhaps one of the most familiar of tin compounds, \(SnF_2\), tin(II) fluoride, goes by the trade name of fluoristan and is found in some fluoride toothpastes.
Chlorine	Acts on tin at room temperature
Bromine	Acts on tin at room temperature
Sulfur	Unites directly with tin when heated
Selenium	Reacts vigorously with tin
Tellurium	Reacts vigorously with tin
Nitrogen	Forms a compound by direct union with tin
Arsenic	Reacts with tin under heat and light
Antimony	Is dissolved by molten tin

Reaction of tin with oxygen

When heated in oxygen, tin produces stannic oxide:

\[Sn_{(s)} + O_{2(g)} \rightarrow SnO_{2(s)} \nonumber \]

Reaction of tin with water (steam)

\[Sn_{(s)} + 2H_2O_{(g)} \rightarrow SnO_{2(s)} + 2H_{2(g)} \nonumber \]

Isotopes

There are 10 known stable isotopes of tin, the most of any elements on the periodic table. This high number of stable isotopes could be attributed to the fact that the atomic number of \(\ce{^{50}Sn}\) is a 'magic number' in nuclear physics.

Table 4: Isotopes of tin

Isotope	% Natural Abundance
112 amu	0.95%
116 amu	14.24%
117 amu	7.57%
118 amu	24.01%
119 amu	8.58%
120 amu	32.97%
122 amu	4.71%
124 amu	5.98%

Allotropes of Tin

Tin has 3 allotropes: alpha, beta and gamma tin. Alpha tin is the most unstable form. Beta tin is the most commonly found allotrope of tin, and gamma tin only exists at very high temperatures.

Oxidation States of Tin

Tin, although it is found in Group 14 of the periodic table, is consistent with the trend found in Group 13, where the lower oxidation state is favored farther down a group. Tin can exist in two oxidation states, +2 and +4, but it displays a tendency to exist in the +4 oxidation state.

Common Compounds of Tin

Tin forms two main oxides, SnO and SnO_{2 (amphoteric).}

Electron Configuration of Tin

Tin has a ground state electron configuration of 1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p⁶5s²4d¹⁰5p² and can form covalent tin (II) compounds with its two unpaired p-electrons. In the three dimensional figure below, the first and most inner electron shell is represented by blue electrons, the second electron shell made up of eight electrons is represented by red electrons, the third shell containing eighteen electrons is represented with green electrons, and the next outer shell again contains eighteen electrons and is represented in purple.

Uses of Tin

Early metal smiths were quick to learn that mixing copper with tin created a more durable metal (bronze) and it is principally for its alloys that tin is valued today. Nearly half of the tin metal produced is used in solders, which are low melting point alloys used to join wires. Solders are important in electrician work and plumbing. Tin is also used as a coating for lead, zinc, and steel to prevent corrosion. Tin cans are widely used for storing foods; the first tin can was used in London in 1812.

Questions

Find the oxidation state of tin in the following compounds:

a. SnCl² Answer:2

b. SnO² Answer:4

Write an equation for the reaction of tin with water. Under what conditions does this reaction take place?

Answer: Sn(s) + 2H₂O(g) → SnO₂(s) + 2H₂(g) Reaction takes place if water is heated to a high temperature to form steam.

Which of these reactions take place?

a. tin with oxygen Answer: YES

b. tin with hydrogen Answer: NO

c. tin with argon Answer: NO

d. tin with chlorine Answer: YES

Arrange the following in order of increasing atomic radius: Sn, K, Ag, C, Pb.

Answer: C<Sn<Pb<Ag<K

Arrange the following in order of decreasing ionization energy: Sn, Si, Pb, I, In.

Answer: Si> I > Sn > In > Pb

References

1. Harwood, William S.; Herring, F. Geoffrey; Madura, Jeffry D.; and Petrucci, Ralph H. General Chemistry: Principles and Modern Applications. Pearson Education, Inc: New Jersey, 2007.
2. Bailar, J.C.; Emeleus, H.J.; Nyholm, Sir Ronald; Trotman-Dickenson, A.F. Comprehensive Inorganic Chemistry. Pergamon Press: Oxford, 1973.
3. Hampel, Clifford A.; Jacobson, C.A. Encyclopedia of Chemical Reactions. Reinhold Publishing Corporation: New York, 1958.
4. Mellor, J.W. A Comprehensive Treatise on Inorganic and Theoretical Chemistry. Longmans, Green and Co.: New York, 1927.

Contributors and Attributions

• Taylor Hughes, (UCSB)