Notes

A note here is one question, answered properly. Not a listicle, not an overview, and not a summary of something covered better elsewhere on the site — a single concrete question, made concrete with real numbers in the first couple of paragraphs, and then built up to an answer rather than asserted.

That makes these different from the other four kinds of page here, and the difference is worth knowing before you pick one. An element page tells you what a substance is. A guide teaches a method you need to be able to reproduce. A comparison settles a choice between two things. A family or period hub explains why a set of elements behaves as a set. A note does none of those. It follows one line of curiosity as far as it goes, which sometimes means ending up somewhere unrelated to where it started.

Where to begin

One of the twelve is roughly twice the length of the others and is the natural entry point. It is about the shape of the table itself — why the rows are the lengths they are, why there is a wide section in the middle and a detached strip at the bottom — and it connects to more of the rest of the site than anything else here. If you have no particular question in mind, start there.

Otherwise, scan the titles. They are written to state the question rather than to tease it, so a title that sounds like something you have wondered about almost certainly is.

What these have in common

Several of them exist because the answer usually given is wrong, or true for the wrong reason. That is the most common trigger for writing one: a stock explanation that is repeated everywhere, sounds satisfying, and does not survive being checked against the numbers. Where that happens the note gives the accurate version and says what the popular version got right, because a wrong explanation that is widely believed is usually wrong in an interesting way.

Each is readable cold. Where a note needs a piece of chemical machinery — a bond energy, a shell structure, a decay mode — it explains that machinery in place rather than assuming you have read a guide first. Links to the relevant guide are there for anyone who wants the full treatment, but no note depends on following one.

Where sources genuinely disagree, they are named and the disagreement is explained rather than smoothed over. That happens more than a casual reader might expect, particularly around who discovered what and in what year, and it is one of the more interesting things about writing on this subject.

Dates

The date on each entry is the date the piece was written, recorded deliberately rather than taken from a file's timestamp — timestamps get rewritten every time a site is copied, which would make every note appear to have been written this morning. The list below runs newest first.