AP Chemistry: Periodic Trends Quiz

Periodic trends describe how elemental properties change as you move across periods (rows) and down groups (columns) in the periodic table. These trends help explain the behavior of elements in chemical reactions and the atomic structure underlying those behaviors. This study focuses on key trends including atomic radius, ionization energy, electronegativity, and electron affinity.

Atomic radius is the distance from an atom’s nucleus to its outermost electron orbital. It decreases from left to right across a period because increasing effective nuclear charge pulls electrons closer, but it increases down a group due to the addition of electron shells. Ionization energy, the energy required to remove the first electron, generally rises across a period owing to higher nuclear charge and smaller atomic radius, and it falls down a group because of larger atomic size and electron shielding.

Electronegativity, a measure of how strongly an atom attracts shared electrons, and electron affinity, the energy released when an atom gains an electron, both tend to increase from left to right across periods and decrease down groups. Exceptions exist, such as chlorine’s higher electron affinity compared to fluorine and variations in electronegativity within group 13. This free quiz assesses your knowledge of these periodic trends, including their causes and notable exceptions.

No signup needed. Facts checked against Wikipedia: Periodic trends.

What the quiz asks

1. How does atomic radius change across a period from left to right?
2. What happens to atomic radius when moving down a group in the periodic table?
3. What is the term for the nuclear charge experienced by electrons after accounting for shielding?
4. How does ionization energy change from left to right across a period?
5. What trend does ionization energy follow when moving down a group?
6. What is electron affinity?
7. How does electron affinity generally change across a period from left to right?
8. What is the trend of electron affinity when moving down a group?
9. Which halogen has the highest electron affinity despite expectations?
10. What is electronegativity?

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