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Why would it take more energy to take 2 electrons from an atom of sodium than it does t take 3 electrons from an atom of aluminum?

Answer 1

Consider the valence shell of sodium versus aluminum.

#"Aluminum, Z = 13"#, with an electronic configuration of #1s^(2)2s^(2)2p^(6)3s^(2)3p^1#, versus #"Natrium, Z = 11":# #1s^(2)2s^(2)2p^(6)3s^(1)# .

The second electron removed from the sodium atom is removed from an inner non-valence shell, which is closer to the nucleus, and thus more tightly held. It makes sense that this electron should require more energy to remove. On the other hand, aluminum has three valence electrons, with #n=3#. The fourth ionization enthalpy of aluminum should be disproportionately high.

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Answer 2

Xavier Avery

The electrons in sodium are in a lower energy level, making them more strongly attracted to the nucleus compared to the electrons in aluminum. Removing electrons from a lower energy level requires more energy.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.