Name: _________________________________________
Period: ___
Atomic Scale Activity
Atoms are small. Protons, neutrons, and electrons are even smaller. The purpose of today’s activity is
to produce a scale model of just how small they are.
Hydrogen is the smallest atom. Below is a diagram of the relative size of a proton to the rest of the
atom:
Å stands for “angstrom.” It is 10-10, or
0.0000000001, meters.
Materials:
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Ruler
Meter stick
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Calculator
Sphere
Instructions:
1) Measure the diameter of your sphere in centimeters. This is your proton. Record this value in
Table 1 on the back.
2) Convert your measurement from #1 into meters. Record this value in Table 1 as well.
3) A hydrogen atom is about 65,000 times bigger than a proton. If your sphere is the size of a
proton, calculate the diameter of a hydrogen atom. Record this value in Table 1 in meters.
4) Your stride length is how long each step you take is. Measure the stride length (in meters) of
each of the members of your table and record them in Table 2.
5) Now calculate how many steps it would take for each person at your table to go across your
“atom.”
Data:
Table 1 – Scale of a Hydrogen Atom
Diameter of sphere (centimeters)
Diameter of sphere (meters)
Diameter of hydrogen atom (meters)
Table 2 – Taking It In Stride
Stride Length (meters)
How many steps to cross a scaled atom
Person #1
Person #2
Person #3
Person #4
Questions:
1) What part of the atom has most of the mass?
2) What takes up most of the space of the atom?
3) Protons and neutrons have approximately the same mass (neutrons are slightly heavier). What
do you think this means about their relative sizes?
4) Thinking back to Rutherford’s experiment: would you expect a lot or a few of the alpha particles
to bounce back after hitting the nucleus?