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êêêêê Canada's ScienceCreative Quarterly recently published an article entitled A dialogue with Sarah, aged 3:In which it is shown that if your dad is a chemistry professor asking “Why?”can be dangerous. By Stephen McNeil êêêêê 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: Why? Dad: Because the water washes the dirt away when Iuse soap. Sarah: Why? Dad: Why do I use soap? Sarah: Yes. Dad: Because the soap grabs the dirt and lets thewater 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 formswater-soluble micelles that trap the otherwise insoluble dirt and oilparticles. Sarah: Why? Dad: Why does soap form micelles? Sarah: Yes. Dad: Soap molecules are long chains with a polar, hydrophilic head and anon-polar, hydrophobic tail. Can yousay ‘hydrophilic’ ? Sarah: Aidrofawwic.(卿穗 或 七─鼠─尾─) Dad: And can you say ‘hydrophobic’ ? Sarah: Aidrofawwic.(苏穗 或 叔─鼠─尾─) Dad: Excellent! The word ‘hydrophobic’ means that it avoids water. Sarah: Why? Dad: Why does it mean that? Sarah: Yes. Dad: It’s 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 personwould say you were gorgo phobic. (希腊语gorgóz(gorgós)是“可怕的”意思，蛇发女妖戈尔贡(gorgon)之名也是出于此) êêêêê(pause) êêêêê Sarah: (rolls her eyes) I thought we weretalking about soap. Dad: We are talking about soap. êêêêê(longish pause) êêêêê 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 highlypolar, and the C-H bonds in the tail are effectively non-polar. Sarah: Why? Dad: Because while carbon and hydrogen have almost the sameelectronegativity, oxygen is far more electronegative, thereby polarizing theC-O bonds. Sarah: Why? Dad: Why is oxygen more electronegative thancarbon and hydrogen? Sarah: Yes. Dad: That’s complicated. There are different answers to that question,depending on whether you’re talking about the Pauling or Mullikenelectronegativity scales. The Pauling scale is based on homo- versusheteronuclear bond strength differences, while the Mulliken scale is based onthe atomic properties of electron affinity and ionization energy. But it reallyall comes down to effective nuclear charge. The valence electrons in an oxygenatom have a lower energy than those of a carbon atom, and electrons sharedbetween them are held more tightly to the oxygen, because electrons in anoxygen atom experience a greater nuclear charge and therefore a strongerattraction to the atomic nucleus! Cool, huh? êêêêê(pause) êêêêê Sarah: I don’t get it. Dad: That’s OK. Neither do most of my students. êêêêê About Stephen McNeil Stephen McNeil is an Assistant Professor of Chemistry at the University of British Columbia Okanagan in Kelowna, British Columbia. To date, he hasbeen interviewed on the radio four times: twice he was talking about chemistry,and twice he was talking about pirates. His favourite element is the element ofsurprise. êêêêê 这是原对话出处： http://www.scq.ubc.ca/a-dialogue-with-sarah-aged-3-in-which-it-is-shown-that-if-your-dad-is-a-chemistry-professor-asking-%E2%80%9Cwhy%E2%80%9D-can-be-dangerous-2/
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