Why are CU ions green or blue?

Copper ions exist in the form of copper(iv) ions tetrahydrate in aqueous solution, the electronic configuration of copper ions is 3d(9), and the copper ions tetrahydrate form a tetracoordination square crystal field, and the wavelength of light released by returning to the ground state after the electron transition is in the blue band, so it is blue.

In the copper chloride solution, the copper ion partially exists in the form of copper tetrahydrate (IV) ions, and part exists in the form of copper tetrachloride (IV) ions, because the chloride ion is a ligand with different intensities from water, so the wavelength of light released by the central copper ion D electron transition of the copper tetrachloride (IV) ion back to the ground state is in the yellow light band, so it is yellow. Therefore, copper chloride shows a mixture of blue and yellow green.

If copper chloride is dissolved in concentrated hydrochloric acid, it shows the yellow color of copper(IV) ions tetrachloride.

In general, the copper ion Cu2+ actually exists in the form of the hydrated ion [Cu(H2O)4]2+ in aqueous solution, and the hydrated copper ion is blue, so most of our common copper salt solutions are blue. In the solution of copper chloride, there are not only hydrated copper ions [Cu(H2O)4]2+, but also chloride ions Cl- combined with copper ions to form tetrachlorocopper complex ions [CuCl4]2-, which is yellow in color. The mixed color of blue and yellow is green.

The copper chloride solution is blue-green because the copper ions form complex ions [CuCl4]2- (yellow) with chloride ions

When complex ions are co-present with copper ions (blue) in solution, they appear green.

The outer electron transition of copper ions is blue-green light.

In the more concentrated CuCl2 solution, the copper ion is combined with the chloride ion to form a coordination ion, which is [CuCl4]2-, which is green, and the reaction is: Cu2+

4cl-[cucl4]2-。In copper sulfate solution, copper ions are combined with water molecules to form ligand ions, called copper tetrahydrate ions, which are blue

Cu(H2O)4]2+, the individual copper ions that do not bind to other molecules of the moisture table are colorless, such as the copper ions in anhydrous copper sulfate are colorless, so anhydrous copper sulfate is white.

The color concentration of copper chloride solution is related, the thinner the concentration, the more obvious the blue, this is because in the dilute concentration of copper chloride solution, Cu2+ is mostly combined with water molecules to form blue [Cu(H2O)4]2+, and the more concentrated the concentration, the more obvious the green, this is because in the large concentration of copper chloride solution, Cu2+ is mostly combined with Cl- to form green [CuCl4]2-, and the moderate concentration of copper chloride solution is generally blue-green.

In general, the copper ion Cu2+ actually exists in the form of the hydrated ion [Cu(H2O)4]2+ in aqueous solution, and the hydrated copper ion is blue, so most of our common copper salt solutions are blue. In the solution of copper chloride, there are not only hydrated copper ions [Cu(H2O)4]2+, but also chloride ions Cl- combined with copper ions to form tetrachlorocopper complex ions [CuCl4]2-, which is yellow in color.

According to the principle of optics, we know that the mixed color of blue and yellow is green, which is why our common general concentration of copper chloride solution is green. If we add water to the copper chloride solution, the concentration of chloride ions in the solution becomes smaller, and the hydrated copper ions increase relatively, and the solution mainly shows the color of hydrated copper ions (blue).

Therefore, the upstairs is green because the concentration is high rather than low.

Answer: The color of some metal ions is related to the medium of the solution. For example, 3-valent chromium ions show a grayish-green color of hydrated chromium ions in water;In the color medium, green and chromium ions are formed, which are shown as green.

Water and Cu2+ ions are blue, while CuCl is white.