Copper(II) ion
Charge: 2+ · Type: Cation · Molar mass: 63.546 g/mol
Made of: copper
How it forms
Copper loses one 4s electron and one 3d electron to form Cu2+. In water the ion binds six water molecules in an octahedral arrangement, and this complex is what produces the familiar blue color.
Naming note
Cu2+ is named copper(II); the traditional name is cupric ion. Copper(I) also exists, so the Roman numeral is required.
Examples in compounds
Copper(II) sulfate
Copper(II) oxide
Copper(II) chloride