368Commercial grades of tin (99.8%) resist transformation because of the inhibiting effect of
the small amounts of bismuth, antimony, lead and silver present as impurities. Alloying
elements such as copper, antimony, bismuth, cadmium and silver increase its hardness.
Tin tends rather easily to form hard, brittle intermetallic phases, which are often
undesirable. It does not form wide solid solution ranges in other metals in general, and
there are few elements that have appreciable solid solubility in tin. Simple eutectic
systems, however, occur with bismuth, gallium, lead, thallium and zinc.Tin becomes a superconductor below 3.72 K. In fact, tin was one of the first
superconductors to be studied; the Meissner effect, one of the characteristic features of
superconductors, was first discovered in superconducting tin crystals.Chemical Inventory................................
Tin resists corrosion from water but can be attacked by acids and alkalis. Tin can be highly
polished and is used as a protective coat for other metals. In this case the formation of a
protective oxide layer is used to prevent further oxidation. This oxide layer forms on pewter
and other tin alloys. Tin acts as a catalyst when oxygen is in solution and helps accelerate
chemical attack.Isotopes
Tin is the element with the greatest number of stable isotopes, ten; these include all those
with atomic masses between 112 and 124, with the exception of 113, 121 and 123. Of
these, the most abundant ones are^120 Sn (at almost a third of all tin),^118 Sn, and^116 Sn,
while the least abundant one is^115 Sn. The isotopes possessing even mass numbers have
no nuclear spin while the odd ones have a spin of +1/2. Tin, with its three common isotopes(^115) Sn, (^117) Sn and (^119) Sn, is among the easiest elements to detect and analyze by NMR
spectroscopy, and its chemical shifts are referenced against SnMe 4.
This large number of stable isotopes is thought to be a direct result of tin possessing an
atomic number of 50, which is a "magic number" in nuclear physics. There are 28
additional unstable isotopes that are known, encompassing all the remaining ones with
atomic masses between 99 and 137.
Aside from^126 Sn, which has a half-life of 230,000 years, all the radioactive isotopes have
a half-life of less than a year. The radioactive^100 Sn is one of the few nuclides possessing
a "doubly magic" nucleus and was discovered relatively recently, in 1994. Another 30
metastable isomers have been characterized for isotopes between 111 and 131, the most
stable of which being 121mSn, with a half-life of 43.9 years.
Etymology
The Latin name stannum originally meant an alloy of silver and lead, and came to mean
'tin' in the 4th century BC—the earlier Latin word for it was plumbum candidum 'white lead'.
History
Tin extraction and use can be dated to the beginnings of the Bronze Age around 3000
BC, when it was observed that copper objects formed of polymetallic ores with different
metal contents had different physical properties.