Cierny zrebec online dating
It has two main allotropes: at room temperature, the stable allotrope is β-tin, a silvery-white, malleable metal, but at low temperatures it transforms into the less dense grey α-tin, which has the diamond cubic structure. The first alloy used on a large scale was bronze, made of tin and copper, from as early as 3000 BC. Pewter, which is an alloy of 85–90% tin with the remainder commonly consisting of copper, antimony, and lead, was used for flatware from the Bronze Age until the 20th century.In modern times, tin is used in many alloys, most notably tin/lead soft solders, which are typically 60% or more tin and in the manufacture of transparent, electrically conducting films of indium tin oxide in optoelectronic applications.However, some organotin compounds (compounds formed from tin and hydrocarbons) can be almost as toxic as cyanide.β-tin (the metallic form, or white tin, BCT structure), which is stable at and above room temperature, is malleable.α-tin has no metallic properties at all because its atoms form a covalent structure in which electrons cannot move freely.It is a dull-gray powdery material with no common uses other than a few specialized semiconductor applications.Tin also occurs in 29 unstable isotopes, encompassing all the remaining atomic masses from 99 to 137.Apart from Sn, cannot be made in significant amounts in the s- or r-processes and are considered among the p-nuclei, whose origins are not well understood yet.
Alloying elements such as copper, antimony, bismuth, cadmium, and silver increase its hardness.
Simple eutectic systems, however, occur with bismuth, gallium, lead, thallium and zinc.
This large number of stable isotopes is thought to be a direct result of the atomic number 50, a "magic number" in nuclear physics.
Cassiterite is usually black or generally dark in color, and these deposits can be easily seen in river banks.
Alluvial (placer) deposits could be easily collected and separated by methods similar to gold panning.