Tuesday, January 25, 2011

Chromium VI: A Human Interest Story

Today I taught nomenclature in my introductory chemistry class and I thought of a wonderful human interest story to make type II transition metals (type II ionic compounds)  all the more relevant. Here it is:

Have you ever seen the movie Erin Brockovitch? If you  haven't, I highly recommend that you do. In this 2000 movie starring Julia Roberts as Erin Brockovitch, a local electricity company releases hexavalent chromium (Chromium VI) into the drinking water of a southern California town. The chromium VI compound is used to prevent corrosion at a cheap price. Not just at a cheap monetary price; at the price of the general health of the surrounding population. This happened from the early '50s through the mid '60s. According to the film, Brockovitch took a low-level clerk position at a law firm to pay her bills amid her rather low-class, somewhat promiscuous, borderline-sketchy lifestyle. Initially, her treatment at the firm was very poor.

Whether it was luck, God, general intelligence or a combination of all of these attributes is unknown. However, in her filing and general administrative duties at the law firm she noticed something odd about documents she was given. She noticed several people in a real estate case had family members with severe health problems (cancer, chronic illness and other complications).

One thing led to another and by the end of the film Brockovitch won the largest class-action settlement in US history against PG&E.

Brockovitch did not have a chemistry background and probably did not know what the health ramifications of Chromium VI might be. Can you imagine how much faster her work might have gone if she had known about this?

Today we looked at Chromium is several different oxidation states. Do you know how to figure out the oxidation state of chromium in a type II ionic compound?

Thursday, January 20, 2011

molecule vs compound. What is the difference?

I realized recently that I use the terms molecule and compound interchangeably. Someone asked me what the difference is and I said, "same thing." This answer is actually incorrect- there is a difference between molecules and compounds although many people (chemists included) use the terms interchangeably. The reason for this is that the two have many things in common.

Both molecules and compounds follow the law of definite proportions. Another way of saying this is to say that in every molecule of water you have one atom of oxygen and two atoms of hydrogen. An alternate way to state this is to say that for every 16 grams of oxygen (per molecule) you always have 2 grams o hydrogen. This is true whether you refer to molecules or compounds.

The terminology differs however when we talk about the type of bonding that occurs in molecular compounds vs other compounds. (Notice how I used the word "compound" in both terms. It implies that something molecular is a compound by nature meaning that it follows the law of definite proportions.) A molecular compound is one that only contains nonmetals (generally) and is held together by the sharing of electrons. Whole molecules might be held rigidly in place by intermolecular forces between molecules but there is never any official chemical bonding between molecules. The sharing of electrons might not be equal. This is the cause of polarity and electronegativity differences. The degree of polarity can actually be calculated on a scale of severity to rate the nature of the polar bond. A bond that has a high enough polarity or electronegativity difference between atoms is actually no longer considered a polar covalent bond but moves into the ranks of the ionic bonds.

Two atoms that have vastly differing electronegativities are bound together by forces of electricity, not the sharing of electrons. It can be thought of as a donation of electrons from one species to the other to create two charged species- positive and negative. The bond is then an electrostatic interaction. One of my students expressed it this way, "It's like the difference between lego legs and a magnet- the ionic bond is the magnet attraction." (and a compound as opposed to a molecular compound)

The "lego legs" illustration refers to the characteristic of molecular bonding in which the sharing of electrons (through overlap of orbitals) creates distinctly arranged atoms that form distinctive shapes with distinctive angles.  In the "magnetic" bonding, the atoms arrange themselves to minimize repulsions and maximize attractions.  In some ways the atoms all float together in magnetic attraction (as if they don't form individual compounds but one big centralized compound made up of many formula units) but if you broke the unit down into pieces it would always have the same ratio of atoms as the compound itself (due to law of definite proportions).

What a talented student! Lego legs vs magnets! I love it.

Randall Knight comes alive in my classroom!

I've finally implemented the idea of instant feedback from the Five Easy Lessons book by Randall Knight. Did I need complex electronic equipment to do it? No. I passed out large index cards and each student divided them into 4 parts. A, B,C, D. Now whenever I want to estimate the number of students who understand my point I ask for people to hold up the appropriate card.

I learned what does NOT work. If you ask the students to give you a rating on the easy/hard nature of the quiz they have no idea what they are talking about. Almost everybody gave me "B" (the quiz was easy). Funny thing that the average was a 65%. Guess they are remiss in the idea of easy vs hard.

Its a subtle change in teaching technique but I already feel a difference. I am connecting with my students on a deeper level. I can't wait to continue.

Saturday, January 01, 2011

The Personal Journals of LM Montgomery: My growing interest in a topic

The evolution of my interest in these literary works spans twenty-five years. For the amount of time I have been interested in this topic I should have received a PhD by now. The unfortunate part of this is that my studies have never been official or affiliated with any kind of university. But, nevertheless it is true, I am fascinated with the life and works of LM Montgomery. Her writing never ceases to lift my spirits in times of trial or provide general entertainment on a rainy day.

When I was ten years old I had very little exposure to television or movies. My viewing was limited to Little House on the Prairie and a few other harmless shows. However, one night I got lucky: Mom and Dad were having a party and needed me to stay upstairs for the entire evening. This meant that not only did I get to watch TV but I got to move the TV into my bedroom to watch it. Since this had never happened before I was thrilled beyond belief. My mom set up the TV in my room to watch the brand new Canadian version of the classic movie Anne of Green Gables. From this moment (was it 1985 or 1986 that it made its debut on television?) I was a hard-core Anne of Green Gables/LM Montgomery fan. Little did I know how my life changed the night I saw the movie for the first time.

Shortly after that I had my own copy of the book, then the entire Anne series (8 books). Not too long after that I had the Emily of New Moon books and a few others. By the time the second movie came out I had parts of the first movie memorized.

As I grew older my enthusiasm waned a bit. Anne seemed a bit juvenile as I got into high school and then during college I was too busy for my old love affair with a fictional character. It wasn't sometime after college that I discovered LM Montgomery  had written novels for adults. There are actually two novels for adults: Blue Castle and A Tangled Web. Both were written while she was living in the Toronto area. A Blue Castle is actually based on a location she visited as a tourist in Toronto; the owners of the hotel have created a museum to commemorate the fame she created out of their hotel in her novel.

When I met my husband one of the things that interested me about him was his Canadian origins. He had lived in Toronto for a number of years before he moved to the United States. I wondered if he had ever heard of famous Anne and her creator. Of course he had not.  (Most men are not overly fond of Anne in the way I am.) I told him about my love affair with LM Montgomery and her origins on Prince Edward Island and he convinced me we should pay her hometown a visit. So we did. And thus began my second love affair with LM Montgomery.

In 2009 we fulfilled a life-long dream of mine and went to Prince Edward Island. Cavendish is just as beautiful as Montgomery describes in her books. We were even able to stay right across the street from the Cavendish cemetery that borders the MacNeill family property. Green Gables is just down the road. Of course the guest house was named after Rachel Lynde (of all people) and ties in with the theme of the different buildings Anne used from Cavendish in her Anne novel. The entire setup is a fairy land.

How much delight it gave me to roam the old MacNeill property so elegantly described in LM's books. The old MacNeill house was torn down long ago - apparently Uncle John was not thrilled with LM's literary fantasies (as obvious in her journals) and rid the property of the house in a utilitarian sweep of the unnecessary. However, John's son and his wife Jenny refurbished the old foundation and created a walking path with a gift shop nearby. You can traverse through the haunted wood to the Green Gables house and walk through the famous Lover's Lane. Surprisingly the Lake of Shining Waters is not there but  over at Park Corner (Campbell home) which is several miles away.

Trips to Rustico and to the North Cape proved to me that there is even more to PEI than Cavendish and Green Gables. I could buy a summer home there it is so beautiful.

It was at the gift shop on the Macneill property that I first became interested in autobiographical information about LM Montgomery. There is a book called the Alpine Path in which she describes her literary career. It is the only such book available by her about her own career and decisions. I read it from cover to cover and found it fascinating. (As an added bonus, John MacNeill's son David MacNeill signed a copy of it for me)

Here in Brampton I discovered that Montgomery and Ewan Macdonald (her husband) served in the Presbyterian Church in Norval. It is about fifteen minutes down the road from us.  In the town there is a bakery owned by the Crawford family; Marion Crawford was one of the children who grew up in the house Montgomery used as her scaffold for Green Gables. The Webbs were cousins of the MacNeill family in Cavendish.  The bakery has a museum in the back dedicated to the memory of LM Montgomery. Of course they sell the 100-year anniversary memorabilia, display her belongings like old teacups and dishes, first-editions of her novels, and display pictures, flyers and other advertisements from the many theatre, church and other functions during her time at the manse. Apparently there is a garden dedicated to her memory- it features her favorite flowers. You can drive by the old Presbyterian manse; however, it is not a museum because the current  pastor of the Presbyterian church (and his family) live there.

The University of Guelph nearby (about 1.5 hour drive from here) owns all of the original journals, scrapbooks, fiction manuscripts and correspondence of LM Montgomery in a special collection that is available for public viewing. Her son Stuart donated the collection shortly before his death in 1982. I am drooling already in anticipation of going there. And go there I will because my in-laws live here. What luck for me!

Meanwhile, The Blue Castle and A Tangled Webb are high on my list of books to read in the near future.

May the love affair continue!