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Chem 203: Chapter 21

Because chapter 21 and 22 are description and full of information I am providing you with this outline to help you determine where to focus your attention.

Chapter 21
Introduction
You should already know how to write electronic configurations for any main group element. An example would be potassium: 1s2 2s2 2p6 3s2 3p6 4s1. This is very important because families (or groups), the vertical columns of the periodic table, share similar electronic configurations and this has a lot to do with their similar chemistry.

You should already know the trends in size, ionization energy, electron affinity and electronegativity. These trends are studied in Chemistry 201. If you don’t remember them I suggest the following review:

http://www.colorado.edu/physics/2000/periodic_table/periodic_properties.html

Another important concept is metals vs non-metals. There is a zig zag line with metalloids on the line.

http://justonly.com/chemistry/chem121/students/powerpoint/tour_of_the_elements.pps
21-1

The concept of polarizability is introduced. It is a ratio of charge to size so you should be able to decide which of two atoms or ions is more or less polarizable. This is a very important concept and sets the foundation for the rest of the chapter.

21-2

You should know that lithium, sodium and potassium are less dense than water. You should know that lithium gives a red flame test and sodium gives a yellow flame test.

Skip the section called: electrode potentials.

Learn reactions 21.2, 21.3, 21.4

Be able to discuss the importance of salt, sodium chloride, in preparing other compounds.

Read about hydration of salts.

WATCH THIS VIDEO

http://www.youtube.com/watch?v=Mx5JJWI2aaw

Be able to give examples of hydrides. Be able to write the Lewis structures for the oxide, peroxide and superoxide ions. Know which alkali metals form which type of oxide.

Go over the solvay process in detail. Know the chemical formulas for brine, lime, slaked lime. Know the major reactants and products for this process.

http://en.wikipedia.org/wiki/File:Solvay_process_reaction_scheme.svg

Skip the section called: alkali metal complexes

Be able to define “soap”.

21-3

Know the main idea of the DOW process for Magnesium i.e. what the starting materials are and what kind of product is made (solid magnesium metal).

Know reaction 21.10

Study the series of reactions 21.14, 21.15, 21.16

Know what Plaster of Paris is.

Skip the section called: Diagonal Relationship of Lithium and Magnesium

21-4

Learn the structure of diborane.

Read the section  called : Aluminum begining on p.946 very carefully.

Read this article: http://en.wikipedia.org/wiki/Ajka_alumina_plant_accident

There are other stories about this industrial accident. It is very interesting to read about what happened.

21-5

Know the allotropes of carbon: graphite, diamond, buckyballs

Be able to compare and contrast the properties of carbon and silicon

Look at the structure of carboxyhemoglobin (figure 21-29) and be able to explain why carbon monoxide is poisonous.

Look over every reaction in this section.

Skip the section called: Zeolites: An Important Class of Aluminosilicates

Skip the section called: Diagonal relationship of Boron and Silicon

Define the term: roasting

Describe the oxidation states of tin and lead.

Know what metals are in bronze and pewter.

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If you go through this list carefully you should be able to perform well on the first exam material on this chapter. I realize there are many, many details here. Don’t forget the most important reason for this chapter – to learn the characters of the elements. This happens best by reading about them.

I strongly recommend the periodic table of videos: http://www.periodicvideos.com/

Watch videos for the elements we covered.

 

Physical Science 107: Say Cheese

First of all I would like to thank the student who took all of these wonderful pictures. Please email me and tell me your name! You deserve some recognition – every photo turned out beautifully.

Today we made cheese to demonstrate the coagulation of proteins with acid. The milk curdles and we end up with curds and whey. We strain the mixture – the curds become cheese and the whey is thrown away.

The process begins with the mixing of milk, buttermilk and lemon juice at a temperature of 175 degrees fahrenheit.

Warming Milk

Warming Milk

The document camera is a great piece of equipment – everyone has a magnified view.

Straining Cheese

Straining Cheese

The cheese needs time to drip away the liquids. We didn’t give it enough time to end up with a hard cheese – we made a soft creamy cheese.
Cheese cloth is used to separate the curds

Cheese cloth is used to separate the curds

The cheese is then tied up.
Dripping over a pan

Dripping over a pan

This Farmer’s cheese can be dressed up with some herbs, a little salt and some pepper.

Farmer's Cheese

Farmer's Cheese

Students are invited to taste the cheese with some crackers.

Cheese and Crackers

Cheese and Crackers

This is a fun way to learn.

 

Chemistry 121: Homework posted

Please log into the website and under the topic: General Handouts and Exercises look for the link to the homework. It is the first link on the page. Let me know if you can’t find it. I’ve chosen problems for Chapters One and Two.

Chemistry 121: First Quiz

We will have a quiz on Thursday August 30th. It will cover definitions of the following terms:

  • hypothesis
  • theory
  • law (scientific law)
  • gas
  • liquid
  • solid
  • sublimation
  • deposition
  • evaporation
  • condensation
  • melting
  • freezing (solidification)

It will also cover the following skills:

  • conversion between decimal form and scientific notation and vice versa
  • counting of significant figures in a number
  • rounding of numbers to the correct number of significant figures
  • adding/subtracting with correct significant figures
  • multiplying/dividing with correct significant figures

Finally you will need to know the values of the following prefixes:

  • kilo
  • centi
  • milli

Chem 121: Getting Started

Well it’s official. I am the instructor for the Chem 121 JK section. The first week of class was unsettling, I’m sure. But we will get focused and get moving this second week. The most important message I have is: Bring that lab book!! We will do a few introductory laboratory exercises on Tuesday. Read Chapters One, Two and Three in the book. This way you will be ready for class. Come with questions and come prepared to discuss what you read.

Physical Science 107: Basic Food Molecules

On Wednesday we continued our discussion of Basic Food Molecules. These are water, carbohydrates, proteins and fats/oils. Students built models of beta-D-glucose, a very important molecule both as a simple sugar and as a building block for cellulose and starch.

beta-D-glucose

beta-D-glucose: black for carbon, red for oxygen and yellow for hydrogen.

Notice that there are three colors in this model – black for carbon, red for oxygen and yellow for hydrogen. Beta-D-glucose is a very important sugar. It occurs naturally in many foods and sucrose (ordinary table sugar) is made from a unit of glucose and a unit of fructose. When ordinary sugar breaks down in the body – glucose is released.

beta-D-glucose

Students construct models to better understand the form of this molecule.

Something to notice about this molecule. Five carbons and one oxygen form a six membered ring. Sticking onto the ring are hydrogen atoms and hydroxyl groups (oxygen and hydrogen). Sugars are sticky – due to all those hydrogens and oxygens which are capable of hydrogen bonding with other molecules. Hydrogen bonding is an attraction of hydrogen on one molecule to electrons on another molecule (typically electrons on oxygen or nitrogen).

Once the students built glucose they used paper models created by Professor Charles Abrams to better understand how these rings form long chains. The chains form sheets. The sheets form layers. And you have cellulose – a carbohydrate that is impossible for humans to digest.

cellulose

Cellulose is made of pleated layers of glucose units.

The stands on each of the four corners are not part of the cellulose structure. They are just there to hold the layers of cellulose in place. If you look closely you will see the rings printed on the paper. These are the same rings that make glucose moledules but they have been flattened into the paper.

You can see another image of a cellulose structure here: http://www.doitpoms.ac.uk/tlplib/wood/structure_wood_pt1.php

The sheets are much larger than shown here – being formed from tens of thousands of glucose rings.

cellulose

Cellulose Model

Putting models together is a great way to begin to picture these important molecules. Cellulose is a structural carbohydrate. It is responsible for the fiber in plants.

cellulose

building models together

Students work in groups so they can discuss their observations and compare their results. In this photograph you can see models of another carbohydrate: amylose. Amylose can form coils (alpha helix form) so look for the rolled up tubes. The carbohydrate begins as a long chain and then, because of hydrogen bonding, curls around itself.

PS107: Food Matters

Class began today and it was lovely to meet all of you. I look forward to an exciting learning experience. To ensure your success it is a good idea to read the blog. It will also be VERY important that you bring your journal to every class so if you have not already done so please purchase a bound composition notebook.

Your homework is to look over the website and read all the documents that are posted. Our lecture on Food Molecules will continue on Wednesday. Enjoy your English 101 class.


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