AP Chemistry: Atomic Structure & Periodicity 3

Question 1

Across a period from left to right, atomic radius generally:

Accepted Answer

decreases

Answer

Increasing nuclear charge pulls electrons in the same shell closer, shrinking the radius.

Question 2

Which element has the highest first ionization energy?

Accepted Answer

Cl

Answer

Chlorine is farthest right in the period, giving it the highest first ionization energy among these.

Question 3

Why does oxygen have a slightly lower first ionization energy than nitrogen?

Accepted Answer

Oxygen's paired 2p electron experiences repulsion

Answer

Removing the paired electron in oxygen's 2p^4 is easier due to electron-electron repulsion.

Question 4

Which element is the most electronegative?

Accepted Answer

Fluorine

Answer

Fluorine is the most electronegative element on the periodic table.

Question 5

The second ionization energy of sodium is much larger than its first because:

Accepted Answer

It removes a core electron from a noble-gas configuration

Answer

After losing one electron, Na+ has a stable neon core, making the next removal very difficult.

AP Practice Test