Chemistry or Cake

Good cake, and some tasty chemistry.  The crazy cake demonstration brings us to the next section in our study of chemical bonding and reaction.  Now that we've delved into the alphabet of chemistry, and learned to create chemistry's words, we can finally begin to make sentences.  I am, of course speaking of chemical equations.  The sentences in our language of chemistry.  

Some of your cakes did not turn out like they should.  This is because some of the ingredients and/or amounts were changed.  In the same way, chemical equations/reactions depend on the amounts involved.  For a reaction to go to completion, the equation must be balanced.  Keep this in mind as we begin to create the final piece of our language of chemistry.

Covalent versus ionic

Something that we haven't spent a lot of time on is the defintion of covalent bonding and covalent compounds.  For our purposes, compounds made from opposite ends of the periodic table are ionic.  They have a metal and a non-metal.  Covalent compounds are made from two non-metallic elements.  So, they are formed on the same end of the periodic table.  Carbon dioxide is a covalent compound, while lithium oxide is ionic.  Both contain oxygen, but only the latter contains a metal.  Keep this in mind when trying to decide between ionic and covalent bonds.

Quizzes

Okay, after grading your quizzes I can see that we're still having a little trouble with ionic bonding.  To help with that, please take some time and go to the Binary Ionics page linked to the right or go here (http://www.chemfiles.com/flash/formulas.html).  It's a relatively simple and fun exercise to help you better visualize what we have to do to form electrically neutral compounds.  Also, just as a heads up.  Bring clothing you don't mind getting dirty in to class next time.  We've got some chemistry to cook up, and it could get a bit messy.

Bonding

We've been discussing bonding in class, specifically ionic bonding.  You'll notice that I've added a few websites that may interest you, one of which should be a big help in understanding the balancing act required when making ionic bonds.  For your visual pleasure, here's a picture illustrating the changes in atomic radius the sodium and chlorine atoms undergo upon ionization.

My challenge to you, for five bonus points:  Describe why the atomic radius of sodium shrinks when it loses an electron, while that of chlorine gets larger when it gains an electron.

Welcome!

Welcome to the inaugural post of the new class blog. As mentioned in the description, you will be able to find new class information (changes to class rules, last-minute assignment changes, etc.) It is also meant to provide me with an additional form of contact between you and your parents. I will be sure to identify posts when they apply only to parents and when they're only meant for students. General posts are for everyone.

You will have the opportunity to post comments in response to a post. But first, some ground rules.
1. Since the purpose of this blog is essentially informative and educational, try to keep your comments on topic.
2. Your parents will be checking these posts and comments as well, so keep the language clean. Parents, I would ask that you do the same.
3. Students, if you want me to answer your question(s), please identify yourself. While I may address anonymous questions, I will concentrate on those from identified students/parents first.

Folks, I essentially assume that you will use common courtesy in your interactions on this blog. However, if I need to, I will add to or modify these ground rules. Otherwise, enjoy the class and I look forward to the year.