Lower Energy Configurations
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Lower Energy Configurations
Hi! I got kind of confused during lecture today when talking about energy levels. My general understanding is that the lower n is, the lower the energy is? For example, 2s < 3s. Is that correct? Just to double check, the numbers (1, 2, 3, etc) are referring to the energy level (AKA n) right? Did I completely misunderstand? Also, there was some exception about "4s before 3d". Was that referring to the energy levels? Why is this the case?
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Re: Lower Energy Configurations
Yes, you are correct, the lower n is, the lower the energy is for that specific principal quantum level. And yes, the numbers (1,2,3...) refer to n which stands for the principal quantum level which defines energy level and the size of the orbital. The exception regarding the 4s and 3d is that 3d electrons actually have lower energy than the 4s electrons, therefore they would go before the 4s electrons when writing the electron configuration. Ex. Scandium is [Ar]3d14s2, NOT [Ar]4s23d1.
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Re: Lower Energy Configurations
Yes, but remember that group 6 and group 11 elements are exceptions to this rule: copper is more stable at [Ar] 3d5 4s1 and chromium is more stable at [Ar] 3d10 4s1.
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Re: Lower Energy Configurations
Hi,
Yes you are correct. The numbers 1, 2, 3 refer to the energy levels for (n), and generally the higher the number the higher the energy. But considering which has higher energy you also need to take into account the s<p<d<f subshells (in increasing energy). As for the exception with the 3d and 4s orbital, due to screening of nuclear charge, the 3d orbital is actually higher in energy than the 4s orbital, though they are very similar. Thus when electrons enter, they would first fill 4s which is lower in energy than 3d (still the Aufbau principle) and then fill the 3d orbital.
Yes you are correct. The numbers 1, 2, 3 refer to the energy levels for (n), and generally the higher the number the higher the energy. But considering which has higher energy you also need to take into account the s<p<d<f subshells (in increasing energy). As for the exception with the 3d and 4s orbital, due to screening of nuclear charge, the 3d orbital is actually higher in energy than the 4s orbital, though they are very similar. Thus when electrons enter, they would first fill 4s which is lower in energy than 3d (still the Aufbau principle) and then fill the 3d orbital.
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Re: Lower Energy Configurations
Yes, you are correct for all those questions! 2s is indeed lower than 3s and the numbers are referring to the energy levels. "4s before 3d" is saying that 4s is actually at a lower energy level than 3d so electrons would fill up the 4s orbital before the 3d orbital.
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