"Nickel-based oxides - nickelates - have long been considered as potential cuprate analogs because the element sits immediately adjacent to copper in the periodic table."

Why would their adjacency (in a row) make them electronic "analogs"? If they're not in the same column they have different valence electron patterns. And more different still when in a molecule with an oxygen atom. Why would they be similar?

Why would their adjacency (in a row) make them electronic "analogs"? If they're not in the same column they have different valence electron patterns. And more different still when in a molecule with an oxygen atom. Why would they be similar?

The article isn't all that well written; you spotted one problem. Nickel actually occurs in two electron configurations: 3d8 4s2 and 3d9 4s1. It's the 4s1 kind that is like copper, which also has a 4s1 shell as the outermost. It's not the adjacency, but the energy levels in the electron shells.

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