Why does tin have a symbol and classical system ion name that does not reflect its common element name?

Question

For example >> Tin's symbol is Sn

One of its classical system ion names is stannous ion.

However, Cobalt's symbol is Co, and one of its classical system ion names is cobaltous ion. Can anyone explain??

Answer 1

Elements known for hundreds of years, like tin, have symbols derived from their Latin names.  Gold, silver, mercury, iron, lead and so on.