activity 5

Activity 5: Density

One of the most common attributes of chemical materials that we observe and feel on a daily basis is the density of materials.  One of the things we notice in the structures of atoms, is that the atom is mostly space, with a small heavy nucleus and very light electrons orbiting the nucleus. So, how heavy something feels is related to how many protons and neutrons are in the nucleus of atoms that make up molecules.  For example, aluminum is much lighter than iron.  The "heaviness" of a material is quantified through a characteristic called density.

For this activity, and future ones, we will introduce the usage of simulations and gaming to aid in our understanding of chemical principles. The simulation package we will utilize can be found at this site:

http://phet.colorado.edu/

There are many of this types of things being developed on the web, I have found this one to be excellent for many reasons.

1. It is free!  This is an activity supported by the National Science Foundation and many others to aid students and educators.

2. I find the interface to be easy and good for entry level science students and even advanced students.  I have found that my 2nd grade son can use these simulations.

3. The science principles covered are very good, and the simulations are quite "real."

4. There is a developing support community for these simulations.  For example there is a section for teachers in which there are pre-developed activities and a way to share your own activities.

For future educators and parents, I encourage you to encourage your future school districts to utilize these types of simulations in science education.  Students tend to become engaged, and it can alleviate some of the costs and struggles of doing actual experiments in the classroom.

To complete Activity 5, complete the tasks below:

1. Run the Build an Atom simulation http://phet.colorado.edu/en/simulation/build-an-atom and build a neutral lithium atom and a neutral boron atom.  Take a picture, or a screen shot, of these two atoms and place them on your blog.  List the number of protons, neutrons and electrons for each. Also look up and post the density for each of the elements on your blog.

The number of protons, neutrons and electrons are all three. The density of the metal lithium is rho = 535 kg/m³ or rho = 0.535 g/cm^3.

The number of protons, neutrons and electrons is all 6.  The density of the element boron is 2,340 kg/m³ or 2.34 g/cm³.

2. Define density and the equation for density and post on your blog.

According to http://wiki.answers.com/Q/What_is_density

3. Run the Density simulation http://phet.colorado.edu/en/simulation/density and complete one(your choice) of the prepared Teaching Ideas and post your results on your blog. The activity you choose should be one of the student intended activities.

PhET- Density Activity- Funsheet

Custom Section                                                                                         

Material	Mass (kg)	Volume (L)	Density (kg/L)	Does it Float?
Styrofoam	0.75 kg	5.00L	0.15kg/L	Yes
Wood	2.00 kg	5.00L	0.40kg/L	Yes
Ice	4.60 kg	5.00L	0.92kg/L	No
Brick	10.00 kg	5.00L	2.00kg/L	No
Aluminum	13.50 kg	5.00L	2.70kg/L	No

1.     In the custom setting, choose the ‘My Object’ option in the material drop down box.  Set the mass of your object to 4 kg.  Adjust the volume to find the minimum volume needed to make the object float.

Volume_________________                Density__________________

2.     How does the density of a large piece of aluminum compare to a small piece?

Same Mass Section

Material	Mass (kg)	Volume (L)	Density (kg/L)	Does it Float?
Blue	5.00kg	5.00L	1.00kg/L	Yes
Yellow	5.00kg	2.50L	2.50kg/L	Yes
Green	5.00kg	400L	1.25.kg/L	No
Red	5.00kg	1.25L	0.80kg/L	No

Same Volume Section

Material	Mass (kg)	Volume (L)	Density (kg/L)	Does it Float?
Blue	6.00 kg	5.00L	1.20kg/L	No
Yellow	8.00kg	5.00L	1.60kg/L	No
Green	4.00kg	5.00L	0.80kg/L	Yes
Red	2.00kg	5.00L	0.40kg/L	Yes

3.  Looking at the data on the previous page, what must be true about the density of

     an object in order for it to float?

The density must be less than one.

Same Density Section:

4.  Calculate the density of the blue object in this section.

     Mass ___4.00__________ Volume____4.00___________ Density________1.00kg/L________

5.  Explain why both the yellow and red objects float when they have different sizes.

It is all about the equation and makes it so the density is less than one.

Mystery Section:

6.  Before you start, pick an object that you think will float.  _______ E____________________

     Pick an object that you think will sink.  __________ C

Material	Mass (kg)	Volume (L)	Density (kg/L)	Does it Float?
A	65.14	3.38	19.27	No
B	0.64	0.64	1.00	Yes
C	4.08	4.08	1.00	Yes
D	3.10	3.10	1.00	Yes
E	3.53	1.00	3.53	No

7.  In the Custom section describe the difference between how Styrofoam and ice  

     floated.  Also explain why you think this is the case?

The Styrofoam was high above the water and the ice was deeper but they both floated and this is the case since their density was less than one.

8.  In the Same Mass Section discuss what was interesting about the blue object’s behavior in the water.

It floated one time and sank the other just because the equation was altered enough so that it sank or floated.

9.  In the Mystery Section, click on the “Show Table” button.  What is the most dense   

     object on the list?  Write its density as well.

The show table was not an option on this simulation.

10.  List something you learned from this activity.

I learn that if the density is less than one it floats and that just because it is small  does not mean it will float.

4. Complete the Mystery Blocks activity on the Density simulation.  Post on your blog the data you collected (mass, volume, and density) and the identification of the material and the known density.
It was done in the data above.

5. Identify and post on your blog the Science Standards that could be met through these activities completed in Activity4

B.12.4 Show how basic research and applied research contribute to new discoveries, inventions, and applications

A.12.4 Construct arguments that show how conflicting models and explanations of events can start with similar evidence

C.12.3 Evaluate* the data collected during an investigation*, critique the data-collection procedures and results, and suggest ways to make any needed improvements