(ELECTRON CONFIGURATION)
Okay so I tried finding the electron configuration for Iron (Fe / 26) and I got 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 and 4d^6 and apparently 4d^6 is wrong and its actually 3d^6
Can someone explain to me why its 3d^6 and not 4d^6 because I thought they were counted by how many rows it goes down. Thanks

Question

emmarose · Answer

The electron configuration for iron (Fe) is $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{6}$, not $4d^{6}$, because electrons fill orbitals in order of increasing energy, not just the row number. The Aufbau principle dictates this order, and the $4s$ orbital is lower in energy than the $3d$ orbital, so it fills first. Therefore, after the $3p$ shell is filled, the next two electrons go into the $4s$ orbital before any fill the $3d$ orbital

gelphielvr · Answer

@emmarose wrote:

The electron configuration for iron (Fe) is $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{6}$, not $4d^{6}$, because electrons fill orbitals in order of increasing energy, not just the row number. The Aufbau principle dictates this order, and the $4s$ orbital is lower in energy than the $3d$ orbital, so it fills first. Therefore, after the $3p$ shell is filled, the next two electrons go into the $4s$ orbital before any fill the $3d$ orbital

ohh so its not based on the rows ...... okay that makes sense Do you know if this periodic table is accurate?

emmarose · Answer

well the 4s orbital is filled before the 3d orbital

iluvpanda · Answer

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iluvpanda · Answer

use this chart, it shud help u a lot more

gelphielvr · Answer

@iluvpanda wrote:

use this chart, it shud help u a lot more

ok thanks

ihy · Answer

@gelphielvr wrote:

@emmarose wrote:

The electron configuration for iron (Fe) is $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{6}$, not $4d^{6}$, because electrons fill orbitals in order of increasing energy, not just the row number. The Aufbau principle dictates this order, and the $4s$ orbital is lower in energy than the $3d$ orbital, so it fills first. Therefore, after the $3p$ shell is filled, the next two electrons go into the $4s$ orbital before any fill the $3d$ orbital

ohh so its not based on the rows ...... okay that makes sense Do you know if this periodic table is accurate?

Yeah it's usually not based on rows.

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