Each unique different kind of its own - mike's web log/comments

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July 30, 2011 | Each unique different kind of its own | 92656 hit(s)

Here's an odd sentence that I found in a chemistry textbook (2003 edition):

Today there are approximately 109 different kinds of atoms, each with its own unique composition.

So many things. Like:

"Today": My admittedly imperfect understanding of the physical world is that elements are elements, and they exist outside of our understanding of time.

"Approximately" 109? Not approximately 108? Not approximately 110? Not exactly 109?

There are "109 different kinds" of atoms? Not just "109 kinds of"? You mean, each kind is different from the others?

Each different kind of atom is moreover distinguished by having its own unique composition? (Isn't uniqueness already part of "different kind of"?)

Each atom has "its own" unique composition, and not the composition of some other atom?

Dunno, seemed a bit ... sloppy ... to me.

Paul A. Schafer 30 Jul 11 - 7:55 PM

Hi Mike -- Regarding your first two points: What you said was true before humans entered the picture. There were 92 elements to start with, but then, over the decades since the late 1930s, labs made several more. The current total is inexact because labs do work, make public claims, and time passes before their claims get certified. The heaviest one on my 2009 chart is Roentgenium, which has a mass of 111. So the writers, writing in 2003, might have been smart to hedge their bets by saying "today" and "approximately."

mike 31 Jul 11 - 12:21 PM

Paul, this is all true, and I actually know this (sort of). But this is the intro chapter of an intro book on chemistry, so it's all well and good that they're hedging, but the result is an odd sentence for what we presume are people who don't have the additional information that you provide. This is long before the book gets into atomic structure, the periodic table, or any other context in which a student might be able to make sense of this sentence; they're still at the stage of defining what an element is.

There are many ways to convey the information that can even include the hedging and without the potential confusion. For example:

Chemists know of 92 naturally occurring atoms, each of which has a unique composition.

-or-

Chemists know of 92 naturally occurring atoms, each of which has a unique composition. (An additional 17 man-made elements are also known.)

-or-

There are approximately 110 naturally occurring atoms, each with a unique composition. (New atoms are occasionally discovered or created.)

etc.

I'd argue that the "today" is a particular dodge, because (as I tell my writer about including "currently" in the docs) that's implicit in the fact the document is published at a particular time. Any statement of fact you make in a book like this is implicitly bracketed with the thought "As far as we know today, ...".

FWIW, I'm not really finding this to be a well-written book generally. Without the little I already know about chemistry, I'm not sure I'd be able to follow their explanations of atoms vs molecules vs mixtures (e.g. marble). I don't know about the rest of the book, but so far this isn't living up to its title of Chemistry: The Easy Way.

mike 31 Jul 11 - 12:22 PM

Scratch "naturally occuring" in the last example, sorry.