[NetBehaviour] A DIALOGUE WITH SARAH, AGED 3...
Michael Szpakowski
szpako at yahoo.com
Sat Aug 25 16:40:20 CEST 2007
:)
m.
--- marc garrett <marc.garrett at furtherfield.org>
wrote:
> A DIALOGUE WITH SARAH, AGED 3: IN WHICH IT IS SHOWN
> THAT IF YOUR DAD IS
> A CHEMISTRY PROFESSOR, ASKING WHY CAN BE
> DANGEROUS.
>
>
http://www.scribd.com/word/html_iframe/1063?guid=27zta2fh7pppm
>
> By Stephen McNeil
>
> - FROM THE ARCHIVES -
>
> SARAH: Daddy, were you in the shower?
>
> DAD: Yes, I was in the shower.
>
> SARAH: Why?
>
> DAD: I was dirty. The shower gets me clean.
>
> SARAH: Why?
>
> DAD: Why does the shower get me clean?
>
> SARAH: Yes.
>
> DAD: Because the water washes the dirt away when I
> use soap.
>
> SARAH: Why?
>
> DAD: Why do I use soap?
>
> SARAH: Yes.
>
> DAD: Because the soap grabs the dirt and lets the
> water wash it off.
>
> SARAH: Why?
>
> DAD: Why does the soap grab the dirt?
>
> SARAH: Yes.
>
> DAD: Because soap is a surfactant.
>
> SARAH: Why?
>
> DAD: Why is soap a surfactant?
>
> SARAH: Yes.
>
> DAD: That is an EXCELLENT question. Soap is a
> surfactant because it
> forms water-soluble micelles that trap the otherwise
> insoluble dirt and
> oil particles.
>
> SARAH: Why?
>
> DAD: Why does soap form micelles?
>
> SARAH: Yes.
>
> DAD: Soap molecules are long chains with a polar,
> hydrophilic head and a
> non-polar, hydrophobic tail. Can you say
> hydrophilic?
>
> SARAH: Aidrofawwic
>
> DAD: And can you say hydrophobic?
>
> SARAH: Aidrofawwic
>
> DAD: Excellent! The word hydrophobic means that it
> avoids water.
>
> SARAH: Why?
>
> DAD: Why does it mean that?
>
> SARAH: Yes.
>
> DAD: Its Greek! Hydro means water and phobic
> means fear of.
> Phobos is fear. So hydrophobic means afraid of
> water.
>
> SARAH: Like a monster?
>
> DAD: You mean, like being afraid of a monster?
>
> SARAH: Yes.
>
> DAD: A scary monster, sure. If you were afraid of a
> monster, a Greek
> person would say you were gorgophobic.
>
> (pause)
>
> SARAH: (rolls her eyes) I thought we were talking
> about soap.
>
> DAD: We are talking about soap.
>
> (longish pause)
>
> SARAH: Why?
>
> DAD: Why do the molecules have a hydrophilic head
> and a hydrophobic tail?
>
> SARAH: Yes.
>
> DAD: Because the C-O bonds in the head are highly
> polar, and the C-H
> bonds in the tail are effectively non-polar.
>
> SARAH: Why?
>
> DAD: Because while carbon and hydrogen have almost
> the same
> electronegativity, oxygen is far more
> electronegative, thereby
> polarizing the C-O bonds.
>
> SARAH: Why?
>
> DAD: Why is oxygen more electronegative than carbon
> and hydrogen?
>
> SARAH: Yes.
>
> DAD: Thats complicated. There are different answers
> to that question,
> depending on whether youre talking about the
> Pauling or Mulliken
> electronegativity scales. The Pauling scale is based
> on homo- versus
> heteronuclear bond strength differences, while the
> Mulliken scale is
> based on the atomic properties of electron affinity
> and ionization
> energy. But it really all comes down to effective
> nuclear charge. The
> valence electrons in an oxygen atom have a lower
> energy than those of a
> carbon atom, and electrons shared between them are
> held more tightly to
> the oxygen, because electrons in an oxygen atom
> experience a greater
> nuclear charge and therefore a stronger attraction
> to the atomic
> nucleus! Cool, huh?
>
> (pause)
>
> SARAH: I dont get it.
>
> DAD: Thats OK. Neither do most of my students.
>
>
>
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