day 3 january 17th 2012 chemistry

Day 3 January 17th 2012

Clickers – let’s try it again!

So, is eyewitness testimony always reliable?

1.Yes2.No

Can Animals Be Superstitious?

Can Animals Be Superstitious?

1.Yes2.No

Definition of Superstition

• that one event leads to the cause of another without any process in the physical world linking the two events.

Why does Tipsy do this?

• Because it seems to work!• Associate two events together• Athletes are often superstitious• Fairy tales, epic stories• Stories about birth, death, healing• Superstition is no substitution for

understanding how the world works.• Scientific method

Clever Hans

Hans could only answer the question if he could see his trainer!

Experimental Designs

Blind experimental design• The experimental subjects do not know

which treatment (if any) they are receiving.

Double-blind experimental design• Neither the experimental subjects nor

the experimenter knows which treatment the subject is receiving.

If you wanted to test if antibacterial soap worked better than regular soap, which answer has the strongest experimental design?1. Have people in the experiment wash with

antibacterial soap first and later with regular soap and compare.

2. Have two groups of people wash with either antibacterial soap or regular soap and compare.

3. Have two groups of people wash with either antibacterial or regular soap, without knowing which type of soap is being used, and compare.

4. Have two groups of people wash with either antibacterial or regular soap, with neither the researchers nor the groups knowing which type of soap is being used, and compare.

If you wanted to test if antibacterial soap worked better than regular soap, which answer has the strongest experimental design?1. Have people in the experiment wash with

antibacterial soap first and later with regular soap and compare.

2. Have two groups of people wash with either antibacterial soap or regular soap and compare.

3. Have two groups of people wash with either antibacterial or regular soap, without knowing which type of soap is being used, and compare.

4. Have two groups of people wash with either antibacterial or regular soap, with neither the researchers nor the groups knowing which type of soap is being used, and compare.

Making Wise Decisions About Concrete Things

Does having access to a textbook help a student to perform better in a biology class?

• Students who had access to a textbook scored an average of 81% ± 8% on their exams…

• …while those who did not scored an average of 76% ± 7%.

What is the average range of scores for students who do not use textbooks while studying?

1. 90 to 100%2. 95%3. 5565%4. 65%

What is the average range of scores for students who do not use textbooks while studying?

1. 90 to 100%2. 95%3. 5565%4. 65%

1. Pseudoscience: individuals make scientific-sounding claims that are not supported by trustworthy, methodical scientific studies.

2. Anecdotal observations: based on only one or a few observations, people conclude that there is or is not a link between two things.

“Four out of five dentists surveyed recommend sugarless gum for their patients who chew gum.”

“How do they know what they know?”

Maybe the statement is factually true, but the general relationship it implies may not be.

Anecdotal Observations do not include a

sufficiently large and representative set of observations of the world

data are more reliable than anecdotes

Science is a way to call the bluff of those who only pretend to knowledge. It is a bulwark against mysticism, against superstition, against religion misapplied to where it has no business being. If we’re true to its values, it can tell us when we’re being lied to.

—Carl Sagan

Chapter 2: Chemistry

Raw materials and fuel for our bodies

Lectures by Mark Manteuffel, St. Louis Community College; Clicker Questions by Kristen Curran, University of Wisconsin-Whitewater

2.1 Everything is made of atoms. An element is a

substance that cannot be broken down chemically into any other substances.

An atom is a bit of matter that cannot be subdivided any further without losing its essential properties.

Atomic Numbers

25 Elements Found in Your Body and the Big 4

What characteristic of an atom gives it its chemical properties?

1. the number of protons2. the number of neutrons3. the number of electrons4. the number of electrons in

its outer orbital

What characteristic of an atom gives it its chemical properties?

1. the number of protons2. the number of neutrons3. the number of electrons4. the number of electrons in

its outer orbital

2.3 Atoms can bond together to form molecules or compounds.

Covalent Bonds

Ions and Ionic Bonds

A sodium ion is positively charged (+1). How many electrons did it originally have in its outer orbital as a sodium atom?

1. 12. 23. 34. 75. 6

A sodium ion is positively charged (+1). How many electrons did it originally have in its outer orbital as a sodium atom?

1. 12. 23. 34. 75. 6

A chloride ion is negatively charged (1). How many electrons did it originally have in its outer orbital as a chlorine atom?

1. 12. 23. 34. 75. 6

A chloride ion is negatively charged (1). How many electrons did it originally have in its outer orbital as a chlorine atom?

1. 12. 23. 34. 75. 6

Potassium chloride (KCl) is formed using ionic bonding. Potassium ions have a net positive charge (+1). Chloride ions have a net negative charge (1). How many electrons were in the outer orbital of the potassium (K) and chloride (Cl) atoms?

1. K=7; Cl=72. K=1; Cl=63. K=7; Cl=64. K=1; Cl=7

Potassium chloride (KCl) is formed using ionic bonding. Potassium ions have a net positive charge (+1). Chloride ions have a net negative charge (1). How many electrons were in the outer orbital of the potassium (K) and chloride (Cl) atoms?

1. K=7; Cl=72. K=1; Cl=63. K=7; Cl=64. K=1; Cl=7

2.4 A molecule’s shape gives it unique characteristics.

Molecular Personalities

Shape determines function• Physical properties such as:

»Taste»Smell

Molecular Interactions and Insect Mating Behavior

Think about our termite lab!