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  • HOW NOT TO TEACH CHEMISTRY– A REVIEW

    Filed at 7:06 am under by dcobranchi

    From the “How to Teach Science” newsletter:

    Lithium’s atomic number is 3.

    It’s in the first column of the periodic table so that means its outer shell has one electron available for bonding.

    Lithium has 3 protons, 3 neutrons, 3 electrons.

    This is the 2nd newsletter I’ve read. Both had factual errors. So, I wrote the author:

    Errr– It has 4 neutrons. AW ~7.

    You really should have someone proof your factoids before sending out the newsletter.

    And her response proves to me that she knows little or no chemistry, certainly not enough to “teach” it:

    Lithium is number 3 on the table. By definition it has 3 of each. In the real world most of the elements rarely have the number of neutrons given them by definition and in pure state or perfect world. Again, this is an introductory newsletter and I teach it as such. I do not choose to go into these situations nor does an introductory chem. book or middle school book. This is my choice and one that suits my audience. If I got into that it would take a while to explain and go into details not necessary. In the coloring book I will have a chapter on neutrons and these variations but I will continue to present it as the text books do in pure form.

    There is no “by definition” concerning the number of neutrons, only protons and electrons. And the number of protons and neutrons isn’t always the same. For instance, beryllium, the next element in the periodic table, exists only as Be-9. That’s 4 protons and 5 neutrons.

    Avoid this one. There are better resources available for teaching chemistry and the periodic table to kids.

    [Full disclosure: The author of the book linked just above is a friend of mine. But I’ve read the book. It’s good. And it’s accurate.]

    10 Responses to “HOW NOT TO TEACH CHEMISTRY– A REVIEW”


    Comment by
    Dawn
    January 8th, 2008
    at 8:11 am

    I’ve downloaded her resources and really liked some of what she had to say about teaching science. I get her newsletter as well but we’ve generally ignored it as we have to wait for it and Google works at our convience. However, the book you reccomend looks awesome and just what I’ve ben hoping to find for some time! Tell your friend thank you!


    Comment by
    Honeybee
    January 8th, 2008
    at 11:29 am

    I have read her previous 4 part lecture and it was full of errors. She claimed that water does not conduct electricity. I wrote to her to explain that deionized, distilled water does not conduct electricity but when the layman thinks about water, they think about tap water or rain water. Tap and rain water contains ions that do conduct electricity. It is dangerous to tell children that water did not conduct electricity. She gave me the same type of lame excuse.

    There were other errors but this one was glaring enough to make me run away from her site.


    Comment by
    Stephanie O
    January 8th, 2008
    at 11:49 am

    Thanks for catching that. I’ve been getting the newsletters, but thought they were pretty lame lists of dry facts. But the idea of teaching young kids about the elements is a good one, so I have to give the author credit for that. I spent about a half hour yesterday discussing molecular orbital theory with my 5 year old, and it was fun! I have a book called The Periodic Table. It’s designed for young kids – my son loves the cute cartoon-y characters that have been drawn for each element. But teaching the periodic table begs for experiments, and my son keeps asking “What do you get if you mix Fluorine and Oxygen?” and things like that. “Fizz, Bubble, & Flash” looks like it could be perfect! I’ve already put it on hold from my library. Thanks!


    Comment by
    Karen
    January 8th, 2008
    at 1:10 pm

    My local library has Fizz, Bubble & Flash! I think I may be the only person to have checked it out. It warmed my little chemical heart when I found. Glad to see a thumbs up from someone with more chem than I have. You should add it’s fun to your list of positives.


    Comment by
    JP
    January 8th, 2008
    at 4:48 pm

    Okay – the chemistry book for kids I have (because we JUST talked bout this yesterday), says that to find the number of neutrons, you subtract the atomic number from the atomic weight, and that gives you the number of neutrons. So, using the Lithium example, 6.941 – 3 = 3.941.

    If the formula given in my book is correct, do I round up to get the 4 neutrons? If so, how do we account for the weight of the electrons? or are they so light that they don’t matter?

    Or, is the formula not correct?

    Thanks, and sorry for the request for the chem lesson.


    Comment by
    Daryl Cobranchi
    January 8th, 2008
    at 5:53 pm

    The formula is correct but misleading. Lithium exists as two naturally occurring isotopes: Li-6 and Li-7. Li-6 weighs 6 amu and Li-7 weighs 7 amu. The weight listed in the periodic table is the arithmetic average of the two isotopes weighted by their relative abundance. Li-7 is about 95% of the naturally occurring lithium. So, the atomic weight for lithium (as listed in the periodic table) would be 7*0.95 + 6*0.05 = 6.95. The listed atomic weight is 6.941.

    Not bad from memory. 🙂


    Comment by
    Daryl Cobranchi
    January 8th, 2008
    at 5:58 pm

    And you’re correct to ignore the electrons. IIRC, an electron is 1/1800 the weight of the proton. Also, the neutron and the proton differ slightly in weight. In fact, the difference is almost exactly the weight of an electron.

    Why that is I leave as an exercise for the reader.


    Comment by
    JP
    January 8th, 2008
    at 9:17 pm

    Thanks!


    Comment by
    Pauline
    January 13th, 2008
    at 1:01 am

    Rainbow Resource carries an *excellent* chem program suitable for interested younger kids but scientifically accurate. I think it’s called “The Elements” – it runs about $25 and you get *a ton* for your money, including a CD of two or three chemistry songs. The activities are very much fun (making electron orbital models out of balloons), and really help the kids “get it”. I taught this program to a group of 3rd-6th grade girls, and they really enjoyed it and learned a *lot*. No need to compromise on the facts to get fun, quality materials.


    Comment by
    Roberta
    April 8th, 2008
    at 10:26 am

    Everything you have said is right on, but I wanted to add one thing. I have found that children do better with science if you give them concrete things to work with and then move to the abstract. Children should be playing with rocks and minerals, or even going through your jewelry box with you. They need to feel gold, silver, tin, copper and aluminum. They need to see that sulfur is yellow. Once they have experienced the elements as real things, then the abstract makes sense. I’m afraid putting the periodic table on the wall isn’t going to have a lasting benefit. But making a periodic table with the actual elements, now thats a memorable project.

    Note: There are several excellent products available which show pictures of the real elements, too.