Classes of metals products with soft bases, which are bases with covalent bonds. The IUPAC Gold Book provides a more general definition of a class (a) metal ion, as "A metal ion that combines preferentially with ligands containing ligating atoms that are the lightest of their Periodic Group", and a class (b) metal as one that combines preferentially with ligands containing ligating atoms other than the lightest of their Periodic Group. Classes of metals Class A metals are metals that form hard acids. Hard acids are acids with relatively ionic bonds. These metals, such as iron, aluminium, titanium, sodium, calcium and the lanthanides,
Metals (album) Metals (album) Metals is the fourth studio album by Canadian singer-songwriter Feist. It was released on September 30, 2011 in Ireland, Austria, Switzerland, Germany, Sweden and Belgium; October 3, 2011 in the United Kingdom; and October 4, 2011 in the United States and Canada. The first single from the album is "How Come You Never Go There", which was released on August 12, 2011. The album was supported by a world tour which started in Amsterdam, Netherlands on October 15, 2011 and finished on October 20, 2012 in Latin America. "Metals" debuted on the US "Billboard" 200 at number 7,