Activity Eight: Exploration of Chemistry

Intro to Isotopes PhET Lab

by Chris Bires

Introduction: Breath in…Breath out.  Again!  When you inhale air, you are not just inhaling a mixture of oxygen, nitrogen, and trace gasses, but a mixture of different oxygen atoms and different nitrogen atoms.  It turns out that all oxygen atoms have the same number of protons, but some may have different numbers of neutrons.  These different-but-still-oxygen atoms are called isotopes.  Some atoms have just two isotopes; some have dozens!

Some handy vocabulary for you to define:

Proton: A stable subatomic particle occurring in all atom's nucleus. Have a positive electric charge.

Neutron: A subatomic particle with no electric charge. Present in all atom's nucleus and has about the same mass as a proton.

Isotope: An element that contains a different number of protons then neutrons. 

Atomic Mass: Is about equivalent to the number of protons and neutrons.

Radioactive: Emitting or relating to the emiision of ionizing radiation or particles. 

Natural Abundance: the abundance isotopes of a chemical element naturally found on a planet.

Procedure: PhETàPlay with the Sims à Chemistry à Isotopes and Atomic Mass

·         Take some time and play with the simulation.  Imagine you are manipulating atoms!  EXCITING!

·         Be sure to activate  and

1.       How do the number of protons change as atomic number increase by one? 

        As the atomic number goes up by one, the number of protons goes up by one.

2.       How does the mass of the atoms change as atomic number increases by one? 

        As the mass of the atom goes up, the atomic number is also increasing. 

3.       What effect does adding a neutron have on the atom’s identity? 

         When you add 1 neutron to the atom, the mass number, atomic mass (amu), and the symbol number also go up. The atom also becomes unstable. 

4.       What effect does adding a neutron have on the atom’s mass? 

        When you add 1 neutron, the mass number disappears. For example, in Helium the mass starts at 4.00260 and after you add 1 neutron, the mass goes to "---" 

5.       Draw the nucleus of the most abundant isotope of each of the following atoms in the boxes below.  Be sure to count and label the protons and neutrons.

6.       Also show the full atomic symbol.  Hydrogen has been done for you. 

Hydrogen: H               Carbon: C                    Oxygen: O                      Neon: Ne

Complete the chart below.  In some cases, you will need to work backwards to fill out missing information.

Isotope Name	Atomic Number	# of Protons	# of Neutrons	Mass Number	Stable? (Y/N)	Ratio of neutrons to protons
Hydrogen-2	1	1	1	2	Yes	1-1
Helium-3	2	2	1	3	yes	1-2
Helium- 5	2	2	3	5	no	3-2
Lithium-6	3	3	3	6	yes	1-1
Lithium - 7	3	3	4	7	no	4-3
Oxygen-16	8	8	8	16	yes	1-1
Oxygen-17	8	8	9	17	yes	9-8
Oxygen-18	8	8	10	18	yes	5-4
Neon-20	10	10	10	20	yes	1-1
Neon-23	10	10	13	23	no	13-10

Analysis Questions              You may need to use the internet to define some terms.

1.       Water is H₂O.  How many isotopes of hydrogen exist in nature?  (even unstable ones) _____7_____

2.       Use the internet to search for “heavy water.”  What is this stuff? 
         It used to be called deuterium oxide or 2h20. It's a form of water that uses hydrogen isotope deuterium instead of the ordinary protium.

3.       How does it behave, compared to ordinary water? 
        Heavy water boils at a little bit lower temperature then ordinary water. Heavy water is also 11% more dense then normal water. 

4.       Does heavy water’s ice float or sink in ordinary water? Why? 
         No, because heavy water is more dense then original water, therefore it will sink. 

5.       Observe the atoms you determined to be unstable.  What can you conclude about the ratio of neutrons to protons and a nucleus’ stability? 
        The ratio of neutrons to protons in an unstable atom, was that the neutrons outnumbered the protons, so the ratio was high to low.

6.       What makes Carbon-14  so useful in “carbon dating” or “radio dating”?'
        Carbon-14 helps show how old something is. Scientists use it to tell how old a fossil or event he earth is. A neutron decays and turns into a proton and electron .

7.       Could a stable isotope of carbon be used in the same way?  Why or why not? 
          No, because the neutron wouldn't decay and leave the extra energy for the proton and neutron.

Molecule Madness

Intended for Fourth Graders
by Taylor Molitor 


To complete this activity, please go to http://phet.colorado.edu/en/simulation/build-a-molecule  and click the Run Now button, to start the simulation.

Part 1: Make Molecules
For the first part, you are going to be using different "kits" (located at the bottom of the simulation) to create the molecules in your collection that are shown on the sidebar to the right. Answer the following questions as you work along with the simulation. Before we start making molecules, let's refresh ourselves on the elements we will be using.

Element	# of Protons	# of Electrons	# of Neutrons	Charge of Atom
Hydrogen
Oxygen
Nitrogen
Carbon

Collection 1:
1. What two elements is Water made of? __________________
2. How many of each element makes up water? ________________________
3. Draw what a water molecule looks like:


4. What two elements is Oxygen made of? __________________
5. How many of each element makes up oxygen? ________________________
6. Draw what a oxygen molecule looks like:



7. What two elements is Hydrogen made of? __________________
8. How many of each element makes up hydrogen? ________________________
9. Draw what a hydrogen molecule looks like:



10. What two elements is Carbon Dioxide made of? __________________
11. How many of each element makes up carbon dioxide? ________________________
12. Draw what a carbon dioxide molecule looks like:



13. What two elements is Nitrogen made of? __________________
14. How many of each element makes up nitrogen? ________________________
15. Draw what a nitrogen molecule looks like:



Part 2: Larger Molecules
For the second part, click on the Larger Molecules tab at the top of the screen. This section is kind of like the first section, but instead you get to build your own molecules. In this section, you are to create molecules of at least three different elements and you can not use ones you already made. You must make one from each kit. Look at my example, if you get stuck.  First let's review the elements we haven't covered yet.

 

Element	# of Protons	# of Electrons	# of Neutrons	Charge of Atom
Chlorine
Fluorine
Boron
Silicon
Sulphur
Phosphorus
Bromine

Example:

1. What molecule did you make? _____Water_______
2. What elements make up this molecule? ____2 Hydrogen and 1 oxygen____
3. Draw your molecule.

      

 Kit 1:
1. What molecule did you make? ________________
2. What elements make up this molecule? ____________________
3. Draw your molecule.



 Kit 2:
1. What molecule did you make? ________________
2. What elements make up this molecule? ____________________
3. Draw your molecule.



 Kit 3:
1. What molecule did you make? ________________
2. What elements make up this molecule? ____________________
3. Draw your molecule.



 Kit 4:
1. What molecule did you make? ________________
2. What elements make up this molecule? ____________________
3. Draw your molecule.



 Kit 5:
1. What molecule did you make? ________________
2. What elements make up this molecule? ____________________
3. Draw your molecule.


  
Kit 6:
1. What molecule did you make? ________________
2. What elements make up this molecule? ____________________
3. Draw your molecule.



 Kit 7:
1. What molecule did you make? ________________
2. What elements make up this molecule? ____________________
3. Draw your molecule.





This lesson will meet the following standards:

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
        Students will be using PhET simulation to answer questions about molecules and to build 3D molecules.

C.4.6 Communicate the results of their investigations in ways their audiences will understand by using charts, graphs, drawings, written descriptions, and various other means, to display their answers
        Students will be taking what they learn and put their answers into graphs or writing down what they are seeing.

D.4.1 Understand that objects are made of more than one substance, by observing, describing and measuring the properties of earth materials, including properties of size, weight, shape, color, temperature, and the ability to react with other substances
         Students will be combining different elements together to create molecules, such as water, oxygen, and carbon dioxide.