Atomic Radius Trends Worksheet

Question 1

Which element is expected to have a larger atomic radius than lithium because it is lower in the same group?

1. Beryllium
2. Sodium
3. Boron
4. Carbon

Question 2

Sodium and chlorine are in the same period. Explain why a neutral chlorine atom is generally smaller than a neutral sodium atom.

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Question 3

What typically changes as you move down a main-group column from one period to the next?

1. The number of occupied principal energy levels increases.
2. The number of protons decreases.
3. The valence electrons move into a lower principal energy level.
4. The occupied energy levels stay the same.

Question 4

Use periodic trends to compare potassium and sodium. State which atom is larger and give a reason.

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Question 5

Which element’s model will have a radius closest to 14 mm?

1. Na
2. Mg
3. Al
4. K

Question 6

Calculate the difference between the listed covalent radii of sodium and aluminum. Include units.

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Question 7

Which comparison directly illustrates a decrease in radius across Period 3?

1. Na to K
2. K to Mg
3. Na to Al
4. Al to K

Question 8

Two model labels for Na and K may have been swapped. The K-labeled model has a smaller radius. Explain how the table can help diagnose the mistake.

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