Name: How Small Are Atoms? Lab

Purpose: To understand the size of atoms based on the mass of atoms.

Hypothesis: In a 5 gram sample of aluminum there are ______atoms.

Procedures:

1.  Obtain 5 grams of aluminum foil. (Tare off a piece of aluminum foil and use a balance to measure the mass. If the mass is less than 5 grams add more foil, if it is greater than 5 grams tare off some of the foil until you have 5.00 grams.) Record the mass in the data table.

2.  Obtain samples of copper, chalk, zinc, and silicon.

3.  Record the mass of each sample in the data table.

Sample of Matter Tested / Mass of Sample in grams / Mass of ONE atom of Sample in grams / Number of Atoms in Sample
Aluminum / 4.48 X 10 -23 grams
Copper / 1.06 X 10 -22 grams
Chromium / 8.64 X 10 -23 grams
Zinc / 1.09 X 10 -22 grams
Silicon / 4.66 X 10 -23 grams

Conclusions:

1.  Determine the number of atoms in each sample by dividing the mass of the sample by the mass of one atom (found in data table).

Aluminum = ______grams = ______atoms of aluminum 4.48 X 10 -23 grams

Copper= ______grams = ______atoms of copper 1.06 X 10 -22 grams

Chromium = ______grams = ______atoms of chromium 8.64 X 10 -23 grams

Zinc = ______grams = ______atoms of zinc 1.09 X 10 -22 grams

Silicon = ______grams = ______atoms of silicon 4.66 X 10 -23 grams

2.  Was your hypothesis correct?

3.  Does the number of atoms in each sample surprise you?

4.  What did this lab help you understand?

5.  Do you think it is possible to see with your naked eye (not using a microscope) a single atom of aluminum?

6.  Guess how many molecules of water do you drink each day?______

7.  Use a graduated cylinder to measure 100 mL of water. Find the mass of the water and record it in the table below.

Sample of Matter Tested / Mass of Sample in grams / Mass of ONE molecule of Sample in grams / Number of Molecules in Sample
Water / 2.99 X 10 -23 grams

8.  Determine the number of molecules of water by dividing the mass of the water by the mass of one molecule of water (found in data table).

Water = ______grams = ______molecules of water 2.99 X 10 -23 grams

9.  Look at the sample of water. Would it be possible to drink 100 mL of water in one day?

10.  Look back at question #6. How close do you think you were to guessing the correct number of water molecules you could drink in one day?

11.  Even though atoms are very small and cannot be seen with your naked eyes it is possible to see them using high power microscopes. Draw what you think a single atom of aluminum look like: