Question

Which of the following statements correctly describe effective nuclear charge (Zeff)? Select all that apply.

A) Zeff increases across a period.
B) Zeff decreases down a group.
C) Zeff is the actual nuclear charge experienced by an electron.
D) Zeff affects atomic size.

Answer 1

The effective nuclear charge (Zeff) correctly describes how it increases across a period, affects atomic size, and represents the actual nuclear charge experienced by an electron. However, it does not decrease down a group; instead, it tends to increase.

Step-by-step explanation:

The concept of effective nuclear charge (Zeff) refers to the pull exerted on a specific electron by the nucleus, taking into account electron-electron repulsions and electron shielding. Zeff increases across a period as we move from left to right because the inner electrons only partially shield the outer electrons from the pull of the nucleus. This stronger pull (higher effective nuclear charge) draws the electrons closer to the nucleus, making the atomic size smaller. Therefore, the correct statements are:

1. A) Zeff increases across a period.
2. D) Zeff affects atomic size.