why Cu , Ag , Au form most of the compound in +2 , +1 & +3 oxidation state respectively ?
Answers
Stability depends on the hydration energy (enthalpy) of the ions when they bond to the water molecules. ... The Cu2+ ion has a greater charge density than Cu+ ion and thus forms much stronger bonds releasing more energy.
Since Group 1 metals always have an oxidation state of +1 in their compounds, it follows that the hydrogen must have an oxidation state of -1 (+1 -1 = 0). Peroxides include hydrogen peroxide, H2O2. This is an electrically neutral compound and so the sum of the oxidation states of the hydrogen and oxygen must be zero.
The +1 ion has tetrahedral or square planar geometry. In solid compounds, copper(I) is often the more stable state at moderate temperatures. The copper(II) ion is usually the more stable state in aqueous solutions. Compounds of this ion, often called cupric compounds, are usually coloured.