Understanding the Electron Configuration of Chromium: Explained [SOLVED]

In summary, the conversation discusses the electron configuration of Chromium and the confusion surrounding its use of the 4th shell instead of filling up the 3rd shell. The expert explains that this is due to the atom becoming more stable when a subshell is either fully filled or half filled. This is also seen in other atoms with anomalous configurations, such as Cu, Nb, and Au. The expert clarifies that by losing one electron to the 4s shell, the 4s subshell becomes half filled and the atom becomes more stable.
  • #1
MichaelXY
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[SOLVED] Electron Configuration

Something in chemistry really has me perplexed. We are doing electron configuration stuff. I think I have a fairly good grip on it after I was able to let go of the Bohr Model.

My question is this. Chromium has 24 electrons which should fit into the first 3 shells 3s, 3p, 3d yet it uses the 4th shell. Why does it not fill up the third shell?

The way it seems it should be to me is 1s2,2s2,2p6,3s2,3p6,3d6 not 3d5,4s1



Thanks
 
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  • #2
if i remember, the atom becomes more stable when a subshell is either fully filled/half filled. so with the 3d6 loses one electron to make it half full and places it in the 4s subshell to make that half filled as well making the atom more stable.
 
  • #3
It does this to reduce electron-electron repulsion (making the atom more stable). There's a whole list of atoms with anomalous configurations, off the top of my head I can think of Cr, Cu, Nb, Mo, Ru, Rh, Ag, La, Ce, Pt, Au, Ac, Th, Pd. There are two or three more.
 
  • #4
In the case of Cr, if it loses the one elctron to the 4s shell, that make 4s half full, but 3d is not half empty. At any rate, I think I see what you are saying.
Thanks
 

1. What is electron configuration?

Electron configuration refers to the arrangement of electrons in an atom or molecule, specifically the way they are distributed among the available energy levels and orbitals.

2. Why is electron configuration important?

Electron configuration is important because it determines the chemical and physical properties of an atom or molecule. It also helps to explain the reactivity and bonding behavior of elements.

3. How do you write electron configurations?

Electron configurations are written using a series of numbers and letters to represent the energy levels and orbitals that electrons occupy. The pattern follows the Aufbau principle, which states that electrons fill the lowest energy levels first.

4. What is the purpose of electron configuration notation?

The purpose of electron configuration notation is to provide a concise and organized way to represent the distribution of electrons in an atom or molecule. It also allows for easy comparison between different elements and their electron configurations.

5. How does electron configuration relate to the periodic table?

The periodic table is organized based on the electron configurations of elements. Elements in the same group or column have similar electron configurations, which can help to predict their chemical and physical properties.

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