Would a neutral \(\mathrm{K}\) atom or a \(\mathrm{K}^{+}\) ion have a more negative value of electron affinity?

Chemical properties are attributes that we cannot observe without causing a substance to change into something else. These properties are a direct result of the arrangements of atoms and their components, especially electrons, within atoms and molecules.

For example, when discussing the chemical properties of potassium (K), we examine its reactivity with water, its valence electron configuration, and its affinity to gain electrons, which includes electron affinity. In our exercise with potassium, we notice that a neutral K atom has a distinct chemical property compared to the K+ ion when it comes to gaining electrons. The neutral atom is much more inclined to accept an additional electron, which is evident from its more negative value of electron affinity.

Understanding chemical properties requires not only an analysis of the atom's current state but also a prediction of its behavior as it gains or loses electrons. This extends to how an atom interacts in reactions, whether through ionic bonding, covalent bonding, or other chemical reactions.

Ionization energy is the energy required to remove an electron from an atom or ion in its gaseous state. It's an essential concept when understanding why atoms form ions, which is a pivotal part of predicting and explaining the chemical behavior of elements.

For instance, in the case of our textbook problem, the ionization energy of potassium (K) is considered when it loses an electron to form a K+ ion. After losing that electron, the ionization energy would be significantly higher for removing another electron, as the electron configuration has become stable resembling that of a noble gas.

This can be connected to electron affinity as well; the K+ ion does not readily accept an additional electron, partly because after losing its outermost electron, the energy required to remove another electron from the now stable configuration increases dramatically. In essence, a higher ionization energy often corresponds with a lower willingness to attract additional electrons, which is seen in our problem with the K+ ion.

Electron configurations refer to the distribution of electrons in an atom's orbitals and provide a foundation for understanding an element’s reactivity and the types of bonds it can form.

Analyzing potassium’s electron configuration, a neutral K atom ends with the electron configuration 4s¹, indicating a single electron in its outermost shell. This electron is relatively loosely bound compared to those in full orbitals, influencing properties such as ionization energy and electron affinity. When potassium forms a K+ ion, it loses this electron, resulting in a noble gas configuration, which is highly stable and nonreactive.

Furthermore, this change in electron configuration from the neutral K atom to the K+ ion illustrates why the ion has a different how electron affinity. While a neutral atom may be inclined to gain an electron to achieve a more stable state, once it has achieved a stable configuration as seen in the K+ ion, the desire to gain additional electrons significantly decreases.