Period 5 element blood cells in the body. Tin is a chemical element with the symbol Sn (for ) and atomic number 50. It is a main group metal in group 14 of the periodic table. Tin shows chemical similarity to both neighboring group 14 elements, germanium and lead and has two possible oxidation states, +2 and the slightly more stable +4. Tin is the 49th most abundant element and has, with 10 stable isotopes, the largest number of stable isotopes in the periodic table. Tin is obtained chiefly from the mineral cassiterite, where it occurs as tin dioxide, SnO. This silvery, malleable
CB military symbol by the United States – signifying crude mustard. In the Second World War the purity of mustard gas was improved through distillation, and this purified chemical warfare agent was designated HD. When it was mixed with a thickener (Agent VV), it was given the symbol HV. Today mustard gas is indicated by the single capital letter H, but HD is still in common use. Military symbols can also reflect the name of where a chemical agent is manufactured. For example, chloropicrin has the symbol PS, which was derived from the British town in which it was manufactured during the First