Today is 8 July 2009 -- We learned "historical chemistry"

We need to remember that chemistry has taken centuries to develop to its current state, and that it continues to evolve.  It is important to know of past accomplishments and how they impact the present as well as the future.  

Who was John Dalton?  Of Dalton's Laws, how many remain unchanged?  When did he formulate his ideas?  Who was Neils Bohr?  What did he do?  Remember, he was dyslexic and still accomplished much.  We discussed atomic structure and the relative size of an atom.  Quick!  If the nucleus was the size of a marble, where would the first electron be?  You learned about atomic number, atomic mass, protons, neutrons and electrons.  You also learned how to find the number of neutrons when the atomic mass and atomic number were known.

We discussed how chemical formulas are written.  For example, when ammonia NH3 (a gas) dissolves in water, it forms ammonium hydroxide, NH4OH.  That compound ionizes to form NH4(positive) and OH(negative).  They react with, for example, sulfuric acid, H2SO4 to form (NH4)2SO4 (where that "2" outside the parenthesis is also a subscript), and water.  

We started discussing scientific notation, significant figures, dimensional analysis (or unit conversion factors), the meaning of the mole and Avogadro's number.  I mentioned that one way of remembering Avogadro's number was to think of it as a telephone number:  "Ava  Gadro:  602-1023."

We saw just how big a number Avogadro's number was in comparison to the number of seconds since the universe formed `13.6 billion years ago:  4.688E17 compared to 6.02E23. 

A student came up with a clever way to remember the rows and columns of the periodic table:  "You climb a column, but run a row!"

You had a brief essay question to ponder:  "From your 'prior knowledge,' of chemistry and what you have been learning in this class, suggest a way to organize elements in some way OTHER than the current idea of the periodic table."

For homework, you were asked to develop your name (or other word) using periodic table symbols, and to send them to me at "abinc@aol.com."  I said I would print them onto thermal paper so you could transfer them to a garment.

Finally, we began to review the text (HOLT, Chemistry), Ch. 1 and 2.  You were asked to study the figures, the tables, the vocabulary and the highlighted words.  REMEMBER TO BRING YOUR BOOK BACK TO CLASS EACH DAY.