Period 2 vs Period 3: Atomic Radius and Ionization Trends (11–20 focus)

Question 1

In Period 3 (elements 11–18), which element has the largest atomic radius?

Accepted Answer

Sodium

Question 2

In Period 3 (elements 11–18), which element has the smallest atomic radius?

Accepted Answer

Argon

Question 3

Which of these Period 3 elements has the largest atomic radius: Na, Mg, or Al?

Accepted Answer

Na

Question 4

Which has the higher first ionization energy: magnesium (Mg, Z=12) or aluminum (Al, Z=13)?

Accepted Answer

Magnesium

Question 5

Between phosphorus (P) and sulfur (S) in Period 3, which element has the higher first ionization energy?

Accepted Answer

Phosphorus

Question 6

Which has a higher first ionization energy: chlorine (Cl) or argon (Ar)?

Accepted Answer

Argon

Question 7

Comparing elements with atomic numbers 11 (Na) and 19 (K), which has the larger atomic radius?

Accepted Answer

Potassium

Question 8

Which has the higher first ionization energy: potassium (K, Z=19) or calcium (Ca, Z=20)?

Accepted Answer

Calcium

Question 9

What is the general trend in atomic radius across a period (left to right) for Periods 2 and 3?

Accepted Answer

Decreases

Question 10

What is the general trend in first ionization energy across a period (left to right) for Periods 2 and 3 (note common exceptions may occur)?

Accepted Answer

Increases

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