Copper Electron Configuration: Everything You Need to Know

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Copper, a transition metal with the symbol Cu, and atomic number 29, is a d-block element in the periodic table. Let us discuss the electronic configuration of Cu.

The electron configuration of copper is : 1s2 2s2 2p6 3s2 3p6 4s1 3d10. Cu has a unique fully-filled 3d configuration in its ground state and so has unique physical and chemical properties. It has a typical fcc structure and is reddish brown coinage metal with excellent heat and electrical conductivity. 

Copper is found abundantly in a variety of minerals. Let us focus on the unique ground state electronic configuration of Cu along with orbital diagram and electronic notation.

How to Write Copper Electron Configuration

Copper is the fourth-period element of group 11 and has 29 electrons. 

  • The primary step is to indicate the energy level of the electrons, and number of electrons present in each orbital (s, p, d, f). Cu has 4 electronic levels and 3 orbitals based on increasing energy of shells according to Aufbau principle.
  • Electronic configuration of copper is written as – 1s2 2s2 2p6 3s2 3p6 4s2 3d9 
  • There are 9 electrons in 3d subshell. Therefore, one of the 4s electrons moves to the 3d subshell to gain stability. Electronic configuration of copper following the Hund’s rule and the Pauli exclusion principle is – 1s2 2s2 2p6 3s2 3p6 4s1 3d10 
  • We see that an electron from 4s orbital moves to 3d orbital (as fully-filled d subshell is more stable), even though it is at a higher energy level. This exception to Aufbau principle is known as the ‘Aufbau exception’ or ‘Aufbau anomaly.’
  • Final electron configuration of Cu following all three rules is – 1s2 2s2 2p6 3s2 3p6 4s1 3d10 

Copper Electron Configuration Diagram

The electron configuration diagram for Cu arranged according to ascending energy levels as per the Aufbau principle, with the arrows indicating the electrons is as follows –

image1 1
Cu electron configuration diagram

Copper Electron Configuration Notation

The electron configuration notation of Copper is [Ar] 4s1 3d10. In the notation, [Ar] represents the electron configuration of argon, which is the previous noble gas. Thus, the notation indicates that the 18 electrons of Ar are present in the configuration of copper, and only the remaining 11 electrons are added.

Copper Unabbreviated Electron Configuration

The unabbreviated electron configuration of copper is written as 1s2 2s2 2p6 3s2 3p6 3d10 4s1. Thus, in Cu, the electrons per shell is 2, 8, 18, 1. The 4s subshell in Cu is only partially filled, while the 3d subshell is completely filled. This is an exception to the normal order of electron filling.

Ground state Copper Electron Configuration

  • The ground state Copper electron configuration is written as 1s2 2s2 2p6 3s2 3p6 3d10 4s1  
  • Copper is a d-block element. The fact that the energy of the 3d subshell in Cu is slightly lower than that of the 4s subshell, causes the electrons to fill the 3d subshell first. Moreover, fully-filled 3d orbital is more stable.
image2 1
Ground state electronic configuration of copper

Excited State of Copper Electron Configuration

The most common excited state electron configuration of copper is [Ar] 3d9 4s2. This excited state occurs when one electron from 3d gets promoted to 4s, keeping the total number of electrons in Cu atom the same.

Ground State Copper Orbital Diagram

The ground state copper orbital diagram is the distribution of 29 electrons in the various atomic orbitals of Cu atom.

  • K-shell contains 2 electrons (1s2)
  • L-shell contains 8 electrons (2s22p6)
  • M-shell contains 18 electrons (3s23p63d10)
  • N-shell contains 1 electron (4s1)
  • The orbital diagram of copper will be –
image3 1
Ground state Copper orbital diagram

Copper 1 ion Electron Configuration

  • The electronic configuration of copper 1 ion is [Ar] 3d10. 
  • The 3d10 configuration gives the cuprous ion (Cu1+) a stable electronic configuration and thus +1 is the most oxidation state of Cu in chemical reactions.

Copper Electron Configuration Exception

Copper shows an exception to the expected electron configuration based on the order of filling of atomic orbitals. 

  • The 3d and 4s orbitals in copper have very similar energies, and so due to interelectronic repulsions, the 3d subshell is first filled before the 4s subshell.
  • In its ground state, the electron configuration of Cu is [Ar] 4s1 3d10, rather than the expected [Ar] 4s2 3d9 configuration based on the Aufbau principle.
  • The 4s orbital is instead only partially filled, and one of its electrons is promoted to the 3d subshell to fully fill it, leading to a more stable configuration.
  • This exception to the Aufbau principle is known as the ‘Aufbau principle inversion.’

Conclusion

Copper is an exceptional metal owing to its distinctive configuration. The second ionization energy of copper is much higher than the first, as the removal of a second electron requires breaking into the completely filled 3d subshell. It is used mainly in electrical wiring and heat exchangers.

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