Which of the following elements in the third period would you expect to have the most negative electron affinity value, and why? Aluminum (Al), because it is a metal with a large atomic radius Chlorine (Cl), because it is a halogen with a high effective nuclear charge Silicon (Si), because metalloids release the most energy when gaining electrons Sodium (Na), because alkali metals only have one electron in the outer energy level

Answer: - Chlorine (Cl)

Explanations: - Electron affinity is the amount of energy released when an electron is added to an element in it's gaseous state. Electron affinity increases in a period on going left to right as the size of the element decreases and it's effective nuclear charge increases and this facilitate an element to accept the electron.

The elements mentioned here in the question belongs to the same group and out of these, chlorine is on the right most side and so it is correct choice.

Hence, Chlorine (Cl), because it is a halogen with a high effective nuclear charge is the correct choice.

The answer is: B) Chlorine (Cl), because it is a halogen with a high effective nuclear charge