3 ms·
I always found it strange that the standard view usually depicts Lanthanum + Actinium on the main block and Lutetium + Lawrencium on the auxiliary. I suppose hi
by XaspR8d 8y ago
I always found it strange that the standard view usually depicts Lanthanum + Actinium on the main block and Lutetium + Lawrencium on the auxiliary. I suppose historically it makes sense that valence was the motivating factor, but at my (totally layperson at this point) glance, the pedagogy seems like it would be simpler to just adopt a more electron-orbital-focused design like the "left step" one.
In any case, it's not like anyone should really be looking at the table placement of an element say to themselves "ah yes now I know everything about how this behaves"; the exceptions are basically an intractable necessity in chemistry.
- jcranmer 8y agoLanthanum + Actinium actually do have the electron configuration you'd expect for a leftmost d block element--their third electron goes into the d block instead of the f block. In practice, the period 6 and 7 elements have quite a few violations of the Afbau principle, and some predictions of period 8 predict some truly anomalous things for electron configuration (e.g., let's start filling up the 9s/p shells before the 8p shell is finished).