Student Exploration: Periodic Trends
Directions: Follow the instructions to complete your group's section of the simulation. Respond to the
questions and... [Show More] prompts in the orange boxes.
New Vocabulary: atomic radius, electron affinity, electron cloud, energy level, group, ion, ionization energy,
metal, nonmetal, nucleus, period, periodic trends, picometer, valence electron
2. Which magnet would be most likely to attract additional paper clips?
3. What is the relationship between the thickness of the book and the ability of the magnet to hold on to and
attract paper clips?
Just as the thickness of a book changes how strongly a magnet attracts a paper clip, the
size of an atom determines how strongly the nucleus attracts electrons. In the Periodic
Trends Gizmo, you will explore this relationship and how it affects the properties of
Part One: Atomic Radius-------------------------------------------------------------
The atomic radius is a measure of the size of the electron cloud, or the region where electrons can be found.
To begin, check that H (hydrogen) is selected in Group 1 on the left. Turn on Show ruler. To measure the
radius, drag one end of the ruler to the proton in the nucleus and the other end to the electron. Click Save
radius to record the value.
1. What is the radius of hydrogen?
Notice that the radius is measured in picometers (pm). A picometer is one
trillionth of a meter.
2. On the right side of the Gizmo, select Li. Connect the right side of the ruler to
the outermost electron, or valence electron. What is the radius of lithium?
Get the Gizmo ready:
● Check that Atomic radius is selected from the
mason cowell Date: 10/5/2020
Magnet B because it’s magnetic pull is strong
167atomic radius increases as you move down a group.
Group 2 have a lot more electrons, as periodic number increases, the amount of electrons
The radius is slightly less when there is more energy levels
I think the radius will decrease as you move across a period.
The radius decreases
Question: What factors affect the radius of an atom?
1. Predict: How do you think the radius of an atom will change as you move down a group (vertical column)
in the periodic table?
2. Collect data: Use the ruler to measure the atomic radii of the group 1 elements. As you do so, count the
energy levels (shown as rings of electrons) in each atom. Record in the table.
Element H Li Na K Rb Cs
Number of energy levels 1 2 3 4 5 6
Atomic radius (pm) 53 167 190 243 265 298
3. Observe: What happens to the radius as you move down group 1?
4. Explore: Turn off Show ruler. Select Li, and then select Be. Observe the radii of the elements in group 2.
Then look at other groups. What pattern do you see?
5. Draw a conclusion: In general, what is the effect of the number of energy levels on the radius of an atom?
6. Predict: How do you think the radius of an atom will change as you move across a period (horizontal row)
in the periodic table?
7. Collect data: Beginning with Na, record the number of energy levels, number of protons, and atomic radius
for each element in period 3 [Show Less]