Principles of Physics

Inverse Square Law

Much of what happens in our bodies is affected not only by biological principles but those of physics, chemistry and mathematics

This is where the gravitational force between any two bodies varies directly as the product of their masses and inversely as the square of the distance between them.

F = G ( m1 m2) d

2

Formula :

Origins of the Inverse Square Law

d = distance between the centers of the spherical masses (meters)

F = net force (newtons)

G = universal constant = 6.67 X 10 -11

N

m = mass (Kilograms)

Pieces of the puzzleAccording to what you read, what are the values for d, F, m and G ?

Revaluate what you have done in working with the assigned problems. Be sure to check that you are using the correct units.

Principles of Physics

Electrostatics:The study of electrical charges that can be collected and held in one place.

•What are the types of charges and how are they represented?

•What is the natural charge of an atom?Describe the structure

•With the addition of energy electrons can be removed from atoms. … if this occurs how is the atom changed?

•Electrons can be transferred but individual charges are neither created nor destroyed•If an electron transfer occurs between two objects the total charge of the two objects remains the same, it is conserved

http://workbench.concord.org/database/activities/157.html - overview

Manipulate the charges on the screen to see how the yellow molecules are effected.1.How must you manipulate the charges to get all of the yellow molecules to go (and stay) on the left?

2. Does the amount of charge affect the time it takes to get all of the molecules to stay to the left of the screen?

3. Can you get all of the molecules to stay to the left even with the addition of a negative charge? Explain your answer

4. Starting with all of the green molecules at a +5 charge choose a spot to put 6 consecutive charges of -5. Then, do the same, but space the – 30 charge out over the green molecules instead of in one place. In which scenario were you able to more effectively get more yellow molecules to the right side of the field? Explain why.

Click on “go to activity”(This may take a few minutes so be patient)

Effect of Electrostatic Interactions on Folding

Now that you have manipulated charges to view their attractive and repellant properties based on charge we will look at how these charges can effect the folding of a protein

Go to

http://workbench.concord.org/database/activities/213.html

Click on “go to activity”

Using the worksheet provided investigate protein folding and answer the questions provided

Bioinformatics: Protein Folding Name: ______________________ Pd:_____

http://workbench.concord.org/database/activities/213.html

Once the page is loaded play both the original chain and the alternately charged chain.

Change arganine to lysine on the last three red arganine molecules and then skip three more arganine from the end and change the next three (the 7th, 8th and 9th molecules from the end of the chain) to lysine as well. 1. How does this change the protein formation? Why?

Reset the modelChange arganine to aspartic acid on the last three red arganine molecules and then skip three more arganine from the end and change the next three (the 7th, 8th and 9th molecules from the end of the chain) to aspartic acid as well. 2. How does this change the protein formation? Why?

Do not reset the modelNow change the first 6 of the arganine chain ( the ones closest to the glutamic acid chain ) to valine.3. How does this change the protein formation?

4. Which change (arganine to aspartic acid or arganine to valine) do you believe caused the biggest change in the folding of the protein? Why?

Go to: http://cnx.org/content/m11467/latest/Read the introduction and the section titled misfolding5. What is the importance of protein folding on protein function?

Coulomb’s Law

Coulomb's law may be stated in scalar form as follows:The magnitude of the electrostatic force between two point electric charges is directly proportional to the product of the magnitudes of each of the charges and inversely proportional to the square of the total distance between the two charges.

Coulomb's law, sometimes called the Coulomb law, is an equation describing the electrostatic force between electric charges.

Formula :F = K ( q q’) d 2

Coulomb’s Law

It was developed in the 1780s by French physicist Charles Augustin de Coulomb and was essential to the development of the theory of electromagnetism.

F = K ( q q’) d 2

Where F = force (newtons)

K = 9.0 x 10 N x m / C (when charge is in coulombs, distance in meters and force in newtons)

q = charge 1 (coulombs)

q’ = charge 2 (coulombs)

d = distance between charges 1 and 2 (meters)

9 22

Pieces of the Formula

http://www.physicsclassroom.com/Class/estatics/U8L3b.cfm

Go to the following web site and read the background information provided. Then answer questions 1 to 7 in your notes. Be sure to show your work.

Then, complete numbers 6 to 13 in the text copy provided, for tomorrow (page 423)

Chemical Bonding

A chemical bond is a mutual electrical attraction between the nuclei and valence electrons of different atoms that binds the atoms together.

Chemical boding occurs due to redistribution of valence electrons in ways that make the atoms more stable.

We will investigate the different types of chemical bonding.

There are two major categories:

1. ___________________

2. ____________________

Bonding where one atom completely “gives up” electrons to another atom

Bonding where two atoms “share” electrons.

Ionic

Covalent

http://mw2.concord.org/public/part2/bondtype/page1.cml

Covalent bonding has two categories:

1. Nonpolar- covalent

2. Polar-covalent There is an uneven distribution of charge (electrons are not shared equally)

There is an even distribution of charge (electrons are shared equally)

Today you will investigate the different types of chemical bonding and how their electronegativity can be used to predict the type of bond present between two given atoms

Go to the web site below beginning with page one work your way through the tutorial and answer the questions provided as you go.

http://workbench.concord.org/database/activities/235.html

Topics we have covered:• inverse square law•Electrostatics•Charges•Polarity•non-polar covalent bonds• polar covalent bonds •ionic bonds •dipole-dipole forces •london dispersion forces •coulomb’s law•protein folding

1. Object A has a positive charge of 6.0 x 10 C. Object B carrying a positive charge of 3.0 x 10 C is 0.030 m away.

a) Calculate the force on Ab) What would be the force if the charge on B were negative?

2. If one object has a mass of 70.0Kg and a second has a mass of 50.0Kg and they are a distance of 20.0 m apart what is the value of the force?

3. If the difference in electronegativity is 2.7 between two atoms what kind of bond do they share?

4. Does a change in charge effect the ability of a protein to fold correctly? If so is this a problem? Explain.

5. What is the difference between an ionic and a covalent bond?

Answer the following questions to review some of the concepts we have covered.

1.8 X 10 N

-6

-6

2

The sign of the force would be (-) in the opposite dirrection

5.84 X 10 N-10

Ionic

Yes, and yes

ionic Bonding where one atom completely “gives up” electrons to another atomBonding where two atoms “share” electrons.covalent

http://workbench.concord.org/database/activities/157.html - overview

http://workbench.concord.org/database/activities/213.html

http://www.physicsclassroom.com/Class/estatics/U8L3b.cfm

http://mw2.concord.org/public/part2/bondtype/page1.cml

http://workbench.concord.org/database/activities/235.html

Some web addresses we have used…..

6. Develop 6 questions concerning this material. Place the questions at the top of the page and the answers to these questions at the bottom of the sheet. Use the web pages we have used and any worksheets or notes we’ve taken to help you in your question creation.

If you develop a good question perhaps it will be on your next exam…

Valence ElectronsThe electrons available to be lost, gained or shared In the formation of chemical compounds

Valence electrons in main group elements

•Groups 1 and 2 have 1 and 2 valence electrons respectively.•The elements of groups 13 to 18 have a number of valence electrons equal to the group number minus 10

Valence electrons hold atoms together in chemical compounds

Determine the number of valence electrons for the following atoms

1. Be2. F3. N4. Ar5. O

Octet RuleCompounds tend to follow the octet rule.

= An atom will share electrons until it is surrounded by 8 valence electrons

•This rule mainly applies to the 2nd row elements•This rule combined with the Nobel gas configuration rule results in compounds which desire 8 electrons in their outer most energy level •The H atom is satisfied with 2 electrons in its outer most energy level.

Using the octet rule determine how many bonds each of the following atoms would like to share in order to attain a valence electron number of 8

1. Be2. F3. N4. Ar5. O

http://crystalclearchemistry.com/organic/concepts/octetrule.php

For more information on the octet rule go to :

Lewis StructuresLewis structures show each atom and its position in the structure of the molecule using its chemical symbol. Lines are drawn between atoms that are bonded to one another (pairs of dots can be used instead of lines). Excess electrons that form lone pairs are represented as pairs of dots, and are placed next to the atoms.

For example:In H2O Oxygen has 8 electrons and Hydrogen has 1. In the Lewis Structure of H2O =• the lines are showing 2 electrons one from oxygen and one from hydrogen• the dots each represent 1 electron

http://faculty.sdmiramar.edu/fgarces/ChemComon/Tutorial/Lewis/LewisTutorial.pdf

Lewis structures with fredVisit the link below to brush up on your lewis structure creation

another way to get to this site is to go to Google and put in : lewis tutorial and miramar college

http://www.astro.virginia.edu/class/oconnell/astr121/im/periodic_table.gif

For a good periodic table try the link below

http://www.stolaf.edu/depts/chemistry/courses/toolkits/123/js/lewis/

http://www.colby.edu/chemistry/PChem/homework/Handin8sans.pdf

Perchlorate is not available on this site … but it is shown on the web site below…. It is the first diagram you see

Check your work

First do the three examples provided to you in your notes. To check your ability to put the lewis structure together for each, go to the following web site and try lewis construction for both nitric acid and carbon dioxide.

On page 6 of 7 there are four lewis structures started for you complete these in your notes

Complete 2, 3 and 4 on page 6.

Be sure to indicate for each:•Oe•TVe•Re

And finally your completed lewis structure. Please use dots for any unpaired valence electrons in your structure.

This is to be turned in for a grade.

Lewis structures with fred