Copper +1 s or d Electron
Does Cu+1 lose its s electron or d electrons? Most
transition metals lose there s electrons when they form a cation.
Copper(I) oxide is a black solid; is this considered a colored compound?
If it is considered a colored compound, why is copper an exception to the
rule of transition metals losing their s electrons?
A number of issues are at play here: First, the outer electron
configuration of [Cu(+1)] in the gas phase is (3d10). See:
The configuration (3d9,4s)
is some 22,000 cm^-1 or (~2.7 ev) higher in energy. Now if you look at the
electron configuration(s) of neutral Cu in the gas phase [Cu(0)], there
are numerous electron configurations all having nearly the same energy.
Now when an atom is placed
in a solid phase environment, such as, Cu(+1)oxide these states get
"scrambled" and it is not possible to give a precise atomic electronic state
or configuration to the atoms. In fact, the CRC Handbook of Chemistry and
Physics lists the color of Cu2O as red-brown. The reason it appears "black"
can arise from two possibilities (one or both): small particle size, and the
broad absorption is so complete as to absorb all the visible light. In
attempting to "make sense" out of chemical bonding, chemists too frequently
do not warn the students that the "simple" bonding schemes we invent are
idealizations and not absolutely accurate descriptions of what is happening
in any given bonding situation. If you look in an intermediate Inorganic
Chemistry text, you will find the topic "ligand field theory" discussed in
detail. This is a model to take into account partly the effect of
surrounding atoms on the energy levels of transition metal compounds. The
bottom line is that the electrons of a given atom in a compound are affected
by its neighbors in solids and solutions, and often an exact description is
not possible or is at best very complicated.
Click here to return to the Chemistry Archives
Update: June 2012