Friday, January 20, 2012

Activity #8


Chemistry Web Quest: Atom Builder                                

In Class:         Open the folder that says “Chemistry Simulations,” Then open “Build an Atom”

Build an Atom
  1. Click the three green “+” signs on the right hand side of the screen
  2. Answer the following questions first.  Then build the atom on the computer to check.
    1. Look at a Periodic Table and find Beryllium (Be)
    2. How many protons are in a neutral Beryllium atom? 4

    1. How many neutrons are in a neutral Beryllium atom? 5

    1. How many electrons are in a neutral Beryllium atom? 4

    1. Build this atom and check that you have built Beryllium.
    2. How many valence electrons does Beryllium have? 2

    1. What will happen to the charge if you remove the valence electrons?  Check and see. It won’t be neutral anymore.

    1. What are charged atoms called? ions

    1. Remove one neutron.
    2. What word appears in the nucleus when you remove a neutron? unstable

    1. What is an atom called when the number of neutrons changes? An isotope

    1. What is the new mass of Beryllium? 8

    1. Look on the right hand side and write down what it says in the symbol box.  Tell what each number means.

8  Atomic Number
4  Mass Number
+2 Charge
Be Element Symbol

  1. Click “Reset All,” and then click the three green “+” signs on the right hand side of the screen.
  2. Answer the following questions first.  Then build the atom on the computer to check.
    1. Look at a Periodic Table and find Nitrogen (N)
    2. How many protons are in a neutral Nitrogen atom? 7

    1. How many neutrons are in a neutral Nitrogen atom? 8

    1. How many electrons are in a neutral Nitrogen atom? 7

    1. Build this atom and check that you have built Nitrogen.
    2. How many valence electrons does Nitrogen have? 5

    1. As a nonmetal, Nitrogen will gain electrons to have a full valence shell.  How many valence electrons will Nitrogen gain to have a full valence shell?  Add this number of electrons. 3

    1. What is the now charge of this Nitrogen ion?  Check and see. -3

    1. Look on the right hand side and write down what it says in the symbol box.  Tell what each number means.

15 Atomic Number
7 Mass Number
-3 Charge
N Element Symbol
2. Lesson Plan

Atom Builder Lesson Plan

1.       Define the following terms:
a.       Proton: positive charged particle

b.      Neutron: particle with no charge

c.       Electron: particle with a negative charge

d.      Ions: charged atom formed by the loss of gain of electrons

e.      Isotope: when an element has the same number of protons but different amounts of neutrons

f.        Valence electrons: electron that is located in the outermost shell

2.       Find Oxygen (O) on the periodic table. Then use the atom builder to figure out how many protons, neutrons, and electrons are needed to create a stable Oxygen atom.
a.       Protons: 8

b.       Neutrons: 8

c.       Electrons: 8

3.       Using the atom builder, what is the mass number of Oxygen? 16

4.       What is the net charge? 0

5.       What do the symbols stand for?
a.       16: Atomic Number

b.      O: Element Symbol

c.       0: Charge

d.      8: Mass Number

6.       If you take away a proton from the atom, it will still be stable.
a.       True
b.      False
7.       What element has 2 protons, 2 neutrons, and 2 electrons? Use the atom builder to find your answer.  Helium
8.       What element has 5 protons, 5 neutrons, and 5 electrons? Use the atom builder to find your answer. Boron
9.       Now, create your own atom using the atom builder. Once you have finished placing the amount of protons, neutrons, and electrons into the atom write down the following.
a.       Protons:
b.      Neutrons:
c.       Electrons:
d.      Mass Number:
e.      Element: 
3. 3 Standards Met

A.4.3 When investigating a science-related problem, decide what data can be collected to determine the most useful explanations


B.4.1 Use encyclopedias, source books, texts, computers, teachers, parents, other adults, journals, popular press, and various other sources, to help answer science-related questions and plan investigations

 C.4.1 Use the vocabulary of the unifying themes to ask questions about objects, organisms, and events being studied

Tuesday, January 17, 2012

Activity #7

2. Complete the Teaching Idea “Concept Questions for Chemistry using PhET”  posted by Trish Loeblein on the pH Scale simulation at PHET (http://phet.colorado.edu/en/simulation/ph-scale). On your blog post the answers with your scientific explanations from the “Clicker Questions pH Scale” posted by Trish.

pH Scale Questions: 
1. B. False
(Explanation: the left is milk, then blood, then a custom liquid like NaOH)
2. D. More than one (Explanation: A. milk, B. blood, C. custom at pH =12)
3. C. (Explanation: A. Custom pH =13  B. water pH =7  C. vomit pH=2)
4. B.(Explanation: A. Water pH =7 B. pH =13  C. soda pop pH =2.5)
5. D. More than one (Explanation: A. Coffee pH =5, B. soda pop pH =2.5, C. custom pH =13)
6. A. increase the pH (Explanation: more water lessens the acidity, so pH goes up)
7. B. decrease the pH (Explanation: more water lessens the basicity , so pH goes down)
8. A. A B C (Explanation: Milk, blood, pH=12)
9. C. B A C (Explanation: 7 pH =13, Water pH =7, soda pop pH =2.5)
10. A. Something was added that made the equilibrium shift left (
Explanation: Since the pH is not 7, then something was added to make the equilibrium shift left. For example, if NaOH was added to water, OH- is immediately in the solution and some of it will react with the H3O+  , so the pH (which is inversely related to [H3O+ ]), goes up. 
If something like HCl were added there would be more H3O+ , which would also cause a shift left, but there would be less OH- , (which is directly related to pH), so the pH is less than 7.)

3. Complete the Teaching Idea “Intro to Strong and Weak Acids and Bases” posted by Chris Bires on the Acid-Base Solutions simulation (http://phet.colorado.edu/en/simulation/acid-base-solutions) and post on your blog your data and answers to the questions posed.




Strong Acid
Weak Acid
Strong Base
Weak Base
Water
pH meter read
(value)
2.00
4.50
12.00
9.50
7.00
pH paper
(color)
Red
Orange
Blue
Green
Yellow
Conductivity
(bright/dim/none)
Bright
Dim
Bright
Dim
None
Exists as Mostly
(ions/molecules)
Ions
Molecules
Ions
Molecules
Ions
Procedure:
This simulation allows you to change the concentration of a strong and weak acid and base.
Complete the table below for some strong acids and bases and weak acids and bases by adjusting the concentration.
Strong Acids
Strength
Initial Acid Concentration (mol/L)
[HA] (mol/L)
[A-] (mol/L)
[H+] (mol/L)
pH
.010 M
negligible
1.00 x 10^-2
1.00 x 10^-2
2
.050 M
negligible
5.00 x 10^-2
5.00 x 10^-2
1.30
.100 M
negligible
1.00 x 10^-1
1.00 x 10^-1
1
1.00 M
negligible
1.00 x 10^0
1.00 x 10^0
0
Weak Acids
Strength (approximately)
Initial Acid Concentration (mol/L)
[HA] (mol/L)
[A-] (mol/L)
[H+] (mol/L)
pH
.015 M
1.50 x 10^-2
3.87 x 10^-5
3.87 x 10^-5
4.41
.150 M
1.50 x 10^-1
1.22 x 10^-4
1.22 x 10^-4
3.91
.015 M
1.36 x 10^-4
1.49 x 10^-2
1.49 x 10^-2
1.83
.150 M
1.17 x 10^-2
1.28 x 10^-1
1.28 x 10^-1
0.86
Strong Bases
Strength
Initial Acid Concentration (mol/L)
[MOH] (mol/L)
[M+] (mol/L)
[OH-] (mol/L)
pH
.010 M
negligible
1.00 x 10^-2
1.00 x 10^-2
12
.050 M
negligible
5.00 x 10^-2
5.00 x 10^-2
12.7
.100 M
negligible
1.00 X 10^-1
1.00 X 10^-1
13
1.00 M
negligible
1.00 x 10^0
1.00 x 10^0
14
Weak Bases
Strength (approximately)
Initial Acid Concentration (mol/L)
[B] (mol/L)
[BH+] (mol/L)
[OH-] (mol/L)
pH
.015 M
1.50 x 10^-2
3.87 x 10^-5
3.87 x 10^-5
9.59
.150 M
1.50 x 10^-1
1.22 x 10^-4
1.22 x 10^-4
10.09
.015 M
1.36 x 10^-4
1.49 x 10^-2
1.49 x 10^-2
12.17
.150 M
1.17 x 10^-2
1.38 x 10^-1
1.38 x 10^-1
13.14
Conclusion Questions:
1.      A strong acid is very concentrated / exists primarily as ions. (circle)
2.      A weak base is a nonelectrolyte / weak electrolyte / strong electrolyte.
3.      A strong base is a nonelectrolyte / weak electrolyte / strong electrolyte.
4.      At the same concentration (Molarity) a strong acid will have a higher / lower / the same pH as a weak acid.
5.      As concentration of a weak acid increases, the pH increases / decreases / remains constant.
6.      As concentration of a weak base increases, the pH increases / decreases / remains constant.
7.      As the concentration of a weak acid increases, the number of ions increases / decreases / remains constant.
8.      As the concentration of a weak acid increases, conductivity increases / decreases / remains constant.
9.      As the strength of a weak acid increases, the proportion of ions to molecules increases / decreases.
10.  As the strength of a weak acid increases, the conductivity increases / decreases / remains constant.
11.  What are the pH values of a weak acid with a concentration of 0.10 and a strong acid with a concentration of 0.01, ten times lower?     Weak acid, 0.10 M: 4.57         Strong Acid, 0.01 M :2
12.  Explain the significance of the results of your calculation above. The weak acid has a higher pH than the strong acid because there is less ions in the weak acid and  therefore has a larger pH.