Electron Configuration Notation:

-shows the arrangment of electrons around the nucleus of an atom.

- helps chemist understanding how elements form chemical bonds.

- can be written using the period table or an electron configuration chart.

How to Write the Electron Configuration for Copper (Cu, Cu+, and Cu2+)

In order to write the Copper electron configuration we first need to know the number of electrons for the Cu atom (there are 29 electrons). Once we have the configuration for Cu, the ions are simple. When we write the configuration we'll put all 29 electrons in orbitals around the nucleus of the Copper atom.

NOTE: Copper is an exception to the rules for writing electron configurations!

In writing the electron configuration for Copper the first two electrons will go in the 1s orbital. Since 1s can only hold two electrons the next 2 electrons for Copper go in the 2s orbital. The next six electrons will go in the 2p orbital. The p orbital can hold up to six electrons. We'll put six in the 2p orbital and then put the next two electrons in the 3s. Since the 3s if now full we'll move to the 3p where we'll place the next six electrons. We now shift to the 4s orbital where we place the remaining two electrons. After the 4s is full we put the remaining six electrons in the 3d orbital and end with 3d9.

Therefore the expected electron configuration for Copper will be 1s²2s²2p⁶3s²3p⁶4s²3d⁹.

Note that when writing the electron configuration for an atom like Cu, the 3d is usually written before the 4s. Both of the configurations have the correct numbers of electrons in each orbital, it is just a matter of how the electronic configuration notation is written (here is an explanation why).

Therefore we have (still incorrect) 1s²2s²2p⁶3s²3p⁶3d⁹4s²

Correct Electron Configuration for Copper (Cu)

Half-filled and fully filled subshell have got extra stability. Therefore, one of the 4s2 electrons jumps to the 3d9. This give us the (correct) configuration of:

1s2 2s2 2p6 3s2 3p6 3d10 4s1

For the Cu+ ion we remove one electron from 4s1 leaving us with: 1s²2s²2p⁶3s²3p⁶3d¹⁰

For the Cu2+ ion we remove a total of two electrons (one from the 4s1 and one form the 3d10) leaving us with

1s²2s²2p⁶3s²3p⁶3d⁹

The configuration notation provides an easy way for scientists to write and communicate how electrons are arranged around the nucleus of an atom. This makes it easier to understand and predict how atoms will interact to form chemical bonds.