Comments on: Organic chemistry textbook: The rhinoceros is a hybrid of a unicorn and a dragon

By: Nicolaj Nylandsted Andersen

Nicolaj Nylandsted Andersen — Thu, 22 Nov 2012 17:17:00 +0000

As it has already been stated, this is an excellent analogy for what resonance contributors really are.

I don’t know where this specific picture is from, but Bruice has used it in her Organic Chemistry (6th ed.) with slightly different pictures.

By: noah django

noah django — Thu, 22 Nov 2012 09:24:00 +0000

Thanks, Textbooks. Thextbooks.

By: Ryan Lenethen

Ryan Lenethen — Wed, 21 Nov 2012 21:09:00 +0000

A: Platypus.

By: B E Pratt

B E Pratt — Wed, 21 Nov 2012 20:36:00 +0000

Back in the early 70′s I had a great introductory college physics text where one the one the first problems was to calculate the distance to Heaven given data from Dante. Not sure they could get away with that these days…..

By: waetherman

waetherman — Wed, 21 Nov 2012 18:07:00 +0000

Wait – is this part of that 5th grade Louisiana textbook quiz? I’m going to say “creationist”

By: Rich Keller

Rich Keller — Wed, 21 Nov 2012 17:20:00 +0000

The dragon picture they used looks like something from the margins of one of my 7th grade school notebooks.

By: DevinC

DevinC — Wed, 21 Nov 2012 17:18:00 +0000

They thought no one would notice if they lifted their illustrations from DeviantArt.

By: Just_Ok

Just_Ok — Wed, 21 Nov 2012 17:06:00 +0000

All the pictures of dragons are copyrighted.

By: thatbob

thatbob — Wed, 21 Nov 2012 17:02:00 +0000

I just don’t understand why they used illustrations of a dragon and a unicorn, instead of a nice photograph like they used for the rhino.

By: Jorpho

Jorpho — Wed, 21 Nov 2012 17:00:00 +0000

The ironic thing is that the unhybridized atomic orbitals probably have a greater claim to being "real" than the hybridized molecular orbitals, which if I am not mistaken are largely just a convenient model in certain applications. (Wikipedia says, "this qualitative view of bonding has been largely superseded by molecular orbital theory when a more detailed analysis is required".)

By: meowmeow

meowmeow — Wed, 21 Nov 2012 16:31:00 +0000

The point is that a dragon and a unicorn don’t exist. They are supposed to be imaginary, because the chemical structures they represent are imaginary as well.

By: meowmeow

meowmeow — Wed, 21 Nov 2012 16:30:00 +0000

The point of this analogy is to show that you can have characteristics of two imaginary things represented in a real-life object. It represents two structures that don’t actually exist (the unicorn and the dragon). The real structure of the molecule (the rhino) just has characteristics of both of the imaginary structures.

There is no good way to describe the inner workings of molecules to 19 year old college students, especially without any basis in quantum mechanics. While this analogy seems ridiculous, it does get the point across, and it has helped plenty of my students understand the weirder parts of organic chemistry.

By: daneyul

daneyul — Wed, 21 Nov 2012 16:25:00 +0000

I dunno. This doesn’t seem like a text book fail to me at all–whimsical, and surprising pertinent to the issue at hand–which in context is specifically two non-existent structures used to describe one that does exist. Wish more text books were as creative in their analogies.

OK, the analogy seems to be used in other places–this one is just for hybridization, but it is used to illustrate the concept of resonance contributors:

“Imagine that you are trying to describe to a friend what a rhinoceros looks like. You might say it looks like a cross between a unicorn and a dragon. Like resonance contributors, the unicorn and dragon do not really exist. Further, like resonance contributors, they are not in equilibrium: a rhinoceros does not change back and forth between the two forms, looking like a unicorn one instant and a dragon the next. The unicorn and dragon are simply ways to describe what the actual structure- the rhinoceros- looks like. Resonance contributors, like unicorns and dragons, are imaginary, not real. only the resonance hybrid, like the rhinoceros, is real.“

By: theophrastvs

theophrastvs — Wed, 21 Nov 2012 16:14:00 +0000

a narwhal and a hippo would’ve been too tedious, i suppose?

By: gjbloom

gjbloom — Wed, 21 Nov 2012 16:13:00 +0000

Students enjoy a little levity in their otherwise dry textbooks. Some authors try to inject a little humor. But publishers seem to believe that books that aren’t 100% dry, factual content will not sell, so they typically reject any such attempts by the author.

By: Zombie Marykate

Zombie Marykate — Wed, 21 Nov 2012 16:12:00 +0000

I think in the image above someone has superimposed their own drawings over top of what the book originally was showing. But I like it anyway. =-) …Going to check out that Tumblr!