What does electron affinity depend on?
A. Both the effective nuclear charge and the number of shells in the atom containing electrons
B. Attraction between the protons and neutrons
C. Only the effective nuclear charge
D. Attraction between the valence electrons and core electrons
To determine what electron affinity depends on, we need to have a basic understanding of electron affinity. Electron affinity refers to the amount of energy released or absorbed when an electron is added to a neutral atom, forming a negatively charged ion. It is a property specific to individual elements.
The correct answer is A. Both the effective nuclear charge and the number of shells in the atom containing electrons.
Explanation:
1. Effective nuclear charge: Electron affinity depends on the effective nuclear charge of an atom. Effective nuclear charge is the net positive charge experienced by an electron in the outermost shell of an atom. It takes into account both the actual nuclear charge and the shielding effect of inner electron shells. The higher the effective nuclear charge, the stronger the attraction between the nucleus and the incoming electron, resulting in a higher electron affinity.
2. Number of shells: Electron affinity also depends on the number of shells in the atom containing electrons. When adding an electron to an atom, it enters the next available electron shell. If the atom already has a highly populated outer shell, it becomes more difficult to add an electron due to electron-electron repulsion. This leads to a lower electron affinity.
Now let's go through the answer choices:
A. Both the effective nuclear charge and the number of shells in the atom containing electrons - This is the correct answer, as explained above.
B. Attraction between the protons and neutrons - The attraction between protons and neutrons is not directly related to electron affinity.
C. Only the effective nuclear charge - This is incorrect because electron affinity also depends on the number of shells, as explained above.
D. Attraction between the valence electrons and core electrons - While there is some truth to this statement, it does not fully explain electron affinity. The effective nuclear charge plays a more significant role in determining electron affinity.