Today is 7 October 2008 -- Who are some of the "Greats" of early 20th century chemistry?

Jonathan C. researched several as part of a class project.  Here are his findings:

John Dalton- he is best known for his work in the development of modern atomic theory, and his research into colour blindness also known as Daltonism. a lunar crater was named  after Dalton.

Albert Einstein- received the 1921 Nobel Prize in Physics for his services to Teoretical Physics and for his discovery of the law of the photoelectric effect. he is also known for his theory of relativity and mass-energy equivalence, E =mc ².

Wolfgang Pauli- found that the current idea that it was magnetic moment of the core of the atom that was responsible for the splitting of the electron energy levels pf the outer electrons was incorrect. proposing a new model, his famous exclusion principle.

Friedrich Hund- discovered an observational rule of atomic chemistry, Rule of Maximum Multiplicity. This rule is used in atomic chemistry, spectroscopy, and quatum chemistry.

Niels Bohr- developed the "planetary" model of the atom. The model introduced the concpet of electron motion to the atomic model.

Amedeo Avogadro- found a resolution to the confusion surrounding atoms and molecules. he believed that particles could be composed of molecules and that molecules could be composed of atoms.

J.J. Thomson- discovered an even smaller and more fundamental partical called the electron.

Dmitri Mendeleev- found that by listing elements in order of increasing relative , their properties recurred in a periodic pattern.He proposed the periodic law and arranged early versions of the periodic table.

Today is 6 July 2009 -- We started our study of chemistry

We:

1.  Prepared a self-study questionnaire and guide.  This guide reflects how you have been studying.  It is what we call a "reflection."  That means we thought about the question and wrote down the way it is for us now.  You were asked to keep the guide.  In a few weeks, we will revisit it and see if your study methods have changed (improved?) based on understanding how you can best study.

2.  Made "notebooks."  The notebooks are for use until we make more permanent ones.  They involved folding a cutting a couple of pieces of paper to make an 8-page booklet.  Always, always, always put your name, date and (when applicable) period/subject on the notebooks.

3.  Read chapter 1 in "Cartoon guide to Chemistry."  This chapter discussed the history of chemistry.  Quick!  What was the very first chemical reaction to impress our ancestors?  (NOTE:  The history of chemistry, even though very briefly presented in the "Guide," is something all chemistry students should know.)

4.  Learned how to "preread."    We will go into more detail when you get your textbooks, and practice summarizing from books, but until then, go over ch. 1 of the Guide again, tomorrow.  This time, use the hints you learned from the "preread" sheet to take notes in your notebook on ch. 1.

5.  Discussed how to write a lab report.  There are 7 parts.  These are (a) statement of purpose, (b) materials and equipment, (c) procedure, (d) results with data, etc., (e) error analysis, (f) conclusions and recommendations, and (g) references. 

6. Had chance to start writing a lab report.  You titled it "The Hollow Penny," which was great title.  You learned how to use a triple beam balance to weigh a penny, then you learned the chemical reaction that would be involved (What was that reaction?) and you carried it out.  You saw the reaction start and you understand that it will go overnight.  You learned how to calculate dilution of an acid, and that the class of compounds called "salts" are composed of a metal and a nonmetal.  You began learning symbols for chemical elements and that the symbols used today are nowhere as complex as the symbols used by early alchemists.

We also discussed how many elements the ancients thought there were (earth, wind, fire and water), and how they realized there was something missing -- something mysterious that they named the "quintessence."  (You should define this, if you don't remember what we said in class.) 

We played with syringes to learn about air pressure. 

We also started talking about how to balance chemical reactions and what happens when something is "oxidized," or burned.  That led into the discussion of the different kinds of "airs" that Joseph Priestley discovered and we mentioned nitrogen, carbon dioxide, hydrogen and oxygen.    Other elements we mentioned today were zinc, sodium, gold, potassium, iron, bromine, chlorine, fluorine and iodine.  (Please make sure you know the symbols for these elements and compounds.) We said a few words about the "father" of the periodic table, Demetri Meendelev.

For tomorrow, we will finish the hollow penny experiment.  You will need to dry and weigh what's left, then write up your report.  

Today is 8 July 2009 -- We learned basics of scientific measurements

You used the "Hollow Penny" lab as a model for studying measurement.  You reweighed your penny and subtracted the final weight from the initial weight.  This gave you the amount of zinc that reacted with the HCl to produce hydrogen gas (H2) and ZnCl2.

We used this information in a discussion of density (density = mass divided by volume) and an introduction to the mole concept (moles = mass divided by atomic mass).  I explained that the mole referred to a specific quantity, like a dozen means 12, and a pair means 2.  I put the following words on the board for you to know:  meniscus and stoichiometry.  We also used the words divisor, density, limiting reagent, coefficient.  (PLEASE LEARN THESE WORDS AND THEIR MEANINGS).  You learned a little about the metric system, that 1 ml = 1 cubic centimeter (cc), and the prefixes:  mili = 1/1000, centi = 1/100, and deci = 1/10.  We gave examples like cent in century, or as in 1/100 of a dollar, and centavo, as 1/100 of a peso.  Millennium has the root "mil" and means 1000, as 1000 years.  Deci means "10" and is the basis of the decimal system. 

I showed you how to solve problems using addition (decimal points line up) or subtraction, and multiplication (with a brief introduction to scientific notation).  You learned that to divide numbers, the denominator (bottom number in a fraction) goes into the numerator (top number). 

We modeled dilution of an acid.  In particular, we had 37% hydrochloric acid (that is hydrogen chloride dissolved in water) and we diluted 20 ml of it to 100 ml with pure water.  That is what we used in the penny lab.  You solve it like this:

                    37%   100 ml

                   ----  =  ------

                     x       20 ml

Cross multiply and divide by 100   for x = (37%)(20ml)/(100ml) = 7.4%

You used the information on the weight of Zn that reacted with the acid solution to calculate the number of moles of zinc.  From there, you calculated the number of moles of ZnCl2.  Then you found the atomic weight of ZnCl2, multiplied it by the number of moles present and obtained the mass (in grams) of the ) ZnCl2. 

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.

Today is 13 July 2009 -- We reviewed standards for chemistry

You had (chemistry) standards 3a, b and c for classwork; standards 4d, e, f and g for homework.  Today I placed you in seven groups and asked each group to explain what a particular standard meant.  Some of you blew off the assignment.  I could see this as I circulated through the room to work with you on understanding the meaning and application.   

Tomorrow you will have a lab based on these standards.  Starting with a piece of magnesium, you will ignite it.  The result is magnesium oxide.  How much magnesium oxide do you expect?  How much do you actually obtain?  Then, you will determine how much hydrochloric acid you need to react with the magnesium oxide to produce magnesium chloride.  What is the other product?  Finally, you will dry the result and calculate the yield.  You need to understand how to determine the molar mass, number of moles and percentages.  You will need to know how to use a balance, and how to work in the lab safely.  

Today is 16 October 2009 -- We are starting our study of Chemistry

Books have not yet been issued.  We are using teacher's notes and a copy of the text projected onto the screen in our room.  We started to cover vocabulary terms used in basic chemistry including "reactant," "product," "chemical," "states of matter," and "chemical reaction."  We discussed and I illustrated reaction types, such as "double displacement," "single displacement" and "synthesis" reactions.  We said that reactions resulted in a change of energy levels that could be observed by (for example) change in pH, color, temperature, and state change (liquid to solid, solid to gas, etc.).  Reactions that release energy are "exothermic."  Those that take energy in are "endothermic."  I gave a homework assignment asking students to place in an empty, plastic water bottle, a piece of steel wool, as from a well-washed steel scrubbing pad (remove as much soap as possible).  Then, cap the bottle and let it sit for a couple of days.  Report on what happened.

We also discussed the history of chemistry.  The conflict between Democritus and Aristotle about "basic units of matter" was described.  Also, how John Dalton found in 1806 that elements were unique substances, not just "earth, wind, fire and water" as had been expounded by Aristotle. 

We are still learning about units of measurement including the prefix "kilo-," "milli-" and how to interconvert them. 

Today is 9 July 2010 -- Mole concept, scientific notation, significant figures review

I offered a refresher of what you were already supposed to have learned in Chemistry A, or prior science classes.  I am concerned that so many students seem not to understand the mole concept, scientific notation and significant figures.  Further, most of you need to drill on basic math operations including long division and exponents.  You had a homework problem:  The diameter of the earth is 8,000 miles.  The equation for the surface area of a sphere (e.g. -- our planet) is S = 4 Pi r^2 (where "r^2" means radius squared).  We solved that.  You were told that the length we call a "meter" was originally set at 1/10,000,000 the distance from the north pole to the equator.  You were reminded that area of a circle is A = Pi r^2 and asked to find the surface area in square meters. 

We discussed the number of particles in a mole:  it is 6.02E23 (where "E23" is a short-hand way of writing "10 to the 23rd power.")  We spoke of ways to memorize the number and how to use it.  Basics of math were covered, like how to divide two numbers (the denominator goes into the numerator; not the other way around).

We started to discuss equilibrium, one of the topics we are to cover in Chem B.  You were to read and summarize Ch. 14, section 3 in your text (HOLT, Chemistry).  Instructions were given on how to "preread" a text.  Homework for the weekend was to preread sections 1 and 2.  I attempted to demonstrate equilibrium with salt solutions and acids, and it didn't work very well. I need purer chemicals to show you.  We'll try again Monday.