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,
Hunan Nonferrous Metals Hunan Nonferrous Metals Hunan Nonferrous Metals Holding Group Co., Ltd. is a nonferrous metals company of China. It is a subsidiary of China Minmetals, which in turn indirectly under supervision of State-owned Assets Supervision and Administration Commission. Some of the assets of the conglomerate was listed in Hong Kong Stock Exchange from 2006 to 2015 as "Hunan Nonferrous Metals Corporation Limited" (SEHK: 2626). (The holding company retained Hunan Yaogangxian Mining Co., Ltd., Hunan Huangshaping Mining Branch and a joint venture (Duddar mine).) However, in 2014 China Minmetals announced the plan to privatization of the listed company, which China Minmetals already