The article begins with "in Earth's deep interior squeeze atoms and electrons so closely together that they interact very differently". The phrase is a little misleading.
The "position" of the inner electron orbitals is mostly determined by quantum rules (it is more complicated, but think that because of something like the Pauli Exclusion Principle the electrons can’t be very close together).
The conductivity of the material depends on the farther electrons, but it is not possible to bring them closer to the core because that space is "filled" with the inner orbitals. The farther orbitals of the atoms get mixed and are transformed into bands, which are not localized in an atom, but span all the crystal.
With more pressure, the nuclear cores get closer, but not very much. The main change is how the farther electron orbitals interact. So at some distance it is possible that some orbital get mixed and at other distance another orbital get mixed. So at some distance the bands are empty or full, and at another distance the bands are partially filled. And that changes the conductivity of the material.
So probabbly the correct way to begin the article is: "in Earth's deep interior squeeze atoms so closely together that their electrons (orbitals) interact very differently".
The "position" of the inner electron orbitals is mostly determined by quantum rules (it is more complicated, but think that because of something like the Pauli Exclusion Principle the electrons can’t be very close together).
The conductivity of the material depends on the farther electrons, but it is not possible to bring them closer to the core because that space is "filled" with the inner orbitals. The farther orbitals of the atoms get mixed and are transformed into bands, which are not localized in an atom, but span all the crystal.
With more pressure, the nuclear cores get closer, but not very much. The main change is how the farther electron orbitals interact. So at some distance it is possible that some orbital get mixed and at other distance another orbital get mixed. So at some distance the bands are empty or full, and at another distance the bands are partially filled. And that changes the conductivity of the material.
So probabbly the correct way to begin the article is: "in Earth's deep interior squeeze atoms so closely together that their electrons (orbitals) interact very differently".