melmichigan Posted May 17, 2013 Share Posted May 17, 2013 Well, I am teaching chemistry next year so I will join. The bad news, I do not know what to use for next year. :( Quote Link to comment Share on other sites More sharing options...
WishboneDawn Posted May 17, 2013 Share Posted May 17, 2013 Well, I am teaching chemistry next year so I will join. The bad news, I do not know what to use for next year. :( Zumdahl's World of Chemistry. Or Introduction to Chemistry. I need some Zumdahl peeps here. Quote Link to comment Share on other sites More sharing options...
Dicentra Posted May 17, 2013 Share Posted May 17, 2013 Hehe - I don't remember ever hearing about a delta chi calculation before today. :lol: Maybe I learned about it in high school, but if I did I have completely blocked it out. So I had the kids explain it to me. Apparently its the difference (delta) in electronegativity (chi) between different elements in a compound (someone want to give me a precise definition of what electronegativity is as it applies to different elements?). Each element gets a number (assigned on a chart - kids did not how these numbers were derived - anyone know?), and then you subtract one from the other and take the absolute value, and violà , the number tells you whether the bond is ionic, covalent, or polar covalent. Cool! Kids did not know how to figure when there were three or more elements in a compound, so I am still in the dark on that too... I've never heard it called a delta chi calculation before today. :) The Wikipedia definition for electronegativity is "a chemical property that describes the tendency of an atom or a functional group to attract electrons (or electron density) towards itself". If I'm allowed to anthropomorphize chemistry, it's how much an element "wants" electrons. Here's how to calculate it. Knowing how to calculate it isn't really necessary unless you're reeeeeeeeeeeeeally into chemistry. The students can just think of it as a scale. The lowest (Pauling's) electronegativity for any element is francium at 0.7 and the highest is fluorine at 3.98. So, francium really doesn't want electrons and fluorine really does. :) An element like magnesium, with an electronegativity of 1.31, wants electrons more than francium but less than fluorine. When two atoms come together, they either share their outer electrons (which forms a covalent bond) or one simply gives up its electrons to the other (which forms an ionic bond). In both cases, you could think of the electrons being shared except in the case of the ionic bond, it's the kind of sharing I do with dh when there's only one cookie left - I get it. :D Covalent bonds are when the electrons are shared more nicely between the two atoms although there can still be unequal sharing - just not as unequal as my cookie sharing. :) The mathematical difference between the electronegativities of two atoms is what the teacher was calling the delta chi calculation. The difference in electronegativity between atoms in a molecule determines whether the bonds are non-polar, polar, or ionic. If the difference is less than 0.4, that tells you the bond between the two atoms is non-polar covalent. If the difference is between 0.4 and 1.7, the bond is polar covalent. If the difference is more than 1.7, the bond is considered ionic. Example: I have a compound made out of magnesium and oxygen. Are the bonds between Mg and O non-polar covalent, polar covalent, or ionic? Answer: The electronegativity of Mg is 1.31. The electronegativity of O is 3.44. 3.44-1.31=2.13 so that tells me that the bond between Mg and O in a compound is an ionic bond. Another example: I have a compound made out of carbon and chlorine. Are the bonds between C and Cl non-polar covalent, polar covalent, or ionic? Answer: C is 2.55 and Cl is 3.16. 3.16-2.55=0.61 so each bond between a C atom and a Cl atom is polar covalent. Why does any of this matter, you may ask? :D We can use the knowledge of whether bonds are non-polar, polar, or ionic to determine the overall polarity of a molecule. (Here's where your students were getting confused, Matryoshka.) When there is more than two atoms in a molecule, you figure out the non-polar/polar/ionic thing for each bond. You then look at all the bonds in a molecule together to determine its overall polarity. (I just skipped over a WHOLE lot of molecular geometry there but I figured the post was getting too detailed as it is. :)) Polarity is very important in determining how compounds "act" with one another. Here's one of the PhET simulations on polarity. Here's a TED talk on how the polarity of water causes it to "act" differently from many other chemicals and, due to those quirky behaviours, life on Earth is possible. Matryoshka, you could direct your students here for understanding how individual bond polarities determine overall polarity - it might help. Quote Link to comment Share on other sites More sharing options...
melmichigan Posted May 17, 2013 Share Posted May 17, 2013 Zumdahl's World of Chemistry. Or Introduction to Chemistry. I need some Zumdahl peeps here. I'll have to find my Cengage passwords and have a look. :) Quote Link to comment Share on other sites More sharing options...
melmichigan Posted May 17, 2013 Share Posted May 17, 2013 Ok, a funny thing happened. I accessed the 6th edition of Zumdahl: Introductory Chemistry, and the video lectures are Thinkwell! :huh: Quote Link to comment Share on other sites More sharing options...
swimmermom3 Posted May 17, 2013 Author Share Posted May 17, 2013 I'll have to find my Cengage passwords and have a look. :) Introduction to Chemistry Quote Link to comment Share on other sites More sharing options...
melmichigan Posted May 17, 2013 Share Posted May 17, 2013 Introduction to Chemistry Nah, I was talking about the instructor passwords. ;) I love Cengage. Quote Link to comment Share on other sites More sharing options...
mom31257 Posted May 17, 2013 Share Posted May 17, 2013 I'll be doing Chemistry with my dd and inviting a friend just for labs, and if it comes out this summer, I'll be doing Apologia's new elementary Chemistry and Physics with ds in a co-op. I'd love to participate in a group. Thanks for thinking of it! Quote Link to comment Share on other sites More sharing options...
PeterPan Posted May 17, 2013 Share Posted May 17, 2013 I'll have to find my Cengage passwords and have a look. :) Mel, how does the Cengage thing work. It looks like you can try to create a faculty acct. Is that what you did? Did it cost $$? Need an access code or is it connected to particular texts, or does one registration get you into EVERYTHING? Quote Link to comment Share on other sites More sharing options...
melmichigan Posted May 17, 2013 Share Posted May 17, 2013 Mel, how does the Cengage thing work. It looks like you can try to create a faculty acct. Is that what you did? Did it cost $$? Need an access code or is it connected to particular texts, or does one registration get you into EVERYTHING? Yes, I have an instructor account. I purchase textbooks from Cengage and worked with my representative at Houghton Mifflin to get my account set up when my DD moved to that level of materials a few years ago. I'm not sure what the process is now, I had to submit my paperwork from the state. There is a lengthy 'terms of agreement' available on the website. Resources vary by book. To date, the resources available have been worth the cost of purchasing books or passkeys from the publisher, be it Cengage/Houghton Mifflin, Pearson, Glencoe, or any of the other publishers that I have worked with. Quote Link to comment Share on other sites More sharing options...
melmichigan Posted May 17, 2013 Share Posted May 17, 2013 Zumdahl's World of Chemistry. Or Introduction to Chemistry. I need some Zumdahl peeps here. I purchased Introductory Chemistry: A Foundation, 6th edition by Zumdahl. :) There aren't many changes from the 5th edition, mostly more review problems. I do like the resources for the 6th edition from the publisher, not all of 5th edition is available online. I'll have to see how it looks. Quote Link to comment Share on other sites More sharing options...
AFwife Claire Posted May 18, 2013 Share Posted May 18, 2013 I would like to join. I've never actually joined a social group, so I don't know what to do, but I'm teaching 6 kids in our little high school co-op next year. We just got done with AP biology, and I have not really thought too deeply yet about what text we'll be using. I have a Zumdahl Chemistry book, as well as BJU. We'll probably use Illustrated Guide to Home Chemistry Experiments for labs. I'm in charge of standardized testing for the families in our big elementary co-op, and that is taking place next week. I figure after that, I will turn my attention to planning for chemistry! Quote Link to comment Share on other sites More sharing options...
swimmermom3 Posted May 18, 2013 Author Share Posted May 18, 2013 I would like to join. I've never actually joined a social group, so I don't know what to do, but I'm teaching 6 kids in our little high school co-op next year. We just got done with AP biology, and I have not really thought too deeply yet about what text we'll be using. I have a Zumdahl Chemistry book, as well as BJU. We'll probably use Illustrated Guide to Home Chemistry Experiments for labs. I'm in charge of standardized testing for the families in our big elementary co-op, and that is taking place next week. I figure after that, I will turn my attention to planning for chemistry! Check your message inbox. I just sent you an invite, otherwise you can just click on the group and join. It's open invitation. We are delighted to have you. Quote Link to comment Share on other sites More sharing options...
swimmermom3 Posted May 18, 2013 Author Share Posted May 18, 2013 I purchased Introductory Chemistry: A Foundation, 6th edition by Zumdahl. :) There aren't many changes from the 5th edition, mostly more review problems. I do like the resources for the 6th edition from the publisher, 5th edition is no longer supported. I'll have to see how it looks. :svengo: What? Does this mean my virgin disc that is still enshrined in shrink wrap, is worthless.? Quote Link to comment Share on other sites More sharing options...
melmichigan Posted May 18, 2013 Share Posted May 18, 2013 :svengo: What? Does this mean my virgin disc that is still enshrined in shrink wrap, is worthless.? Or priceless? The companion site is available for 5th edition, but I can't find where you can get coursemate for that edition. There isn't an option to buy a passkey for that edition and a lot of the instructor materials aren't available for it. Right now you can get access for the 6th and 7th edition so I have doubts they will go back and make the same resources available for an outdated edition. If you have them on disc then you might be ahead of the game. ;) ETA: I reworded the comment swimmermom3 quoted from to avoid confusion. 5th edition is supported in some regards, but not everything is available online anymore. Quote Link to comment Share on other sites More sharing options...
KimberlyI Posted May 27, 2013 Share Posted May 27, 2013 I have not yet participated in a social group, but this sounds wonderful!! Our plan, until last week, for DS was Physics for this upcoming year but we changed to Chemistry for 10th and AP Chemistry for 11th. After discovering these chemistry threads and social group I"m so glad we changed our plan (even though it was a little last minute for me!) High school science is not my strength so I'm not sure how much I'll be able to contribute. I'm extremely grateful for the generosity of those of you who are strong in this area. Quote Link to comment Share on other sites More sharing options...
jibaker103 Posted May 27, 2013 Share Posted May 27, 2013 I am definitely in!!! My ds 17 will be doing chemistry either through co-op or at home. Since I don't know anything about the subject we are leaning so far over that we might tip toward the co-op, lol!!! Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.