What are the bond type for atoms with element Tin?
element Tin refers to element = 'sn'; double bond refers to bond_type = ' = '; single bond refers to bond_type = '-'; triple bond refers to bond_type = '#'
SELECT DISTINCT T3.bond_type FROM atom AS T1 INNER JOIN connected AS T2 ON T1.atom_id = T2.atom_id INNER JOIN bond AS T3 ON T3.bond_id = T2.bond_id WHERE T1.element = 'sn'