Question

If the electron affinity for an element is a negative number, does it mean that the anion of the element is more stable than the neutral atom? Explain.

Short answer

If the electron affinity for an element is a negative number, it means that the anion of the element is more stable than the neutral atom. This is because energy is released when an electron is added to the neutral atom, which contributes to the stability of the anion. The larger the negative electron affinity value, the more stable the anion of that element is compared to the neutral atom.

Step-by-step solution

Define Electron Affinity

Electron affinity is the amount of energy released or absorbed when an electron is added to an isolated gaseous atom to form a negatively charged ion or anion. It is expressed in units of kilojoules per mole (kJ/mol).

Explain Negative and Positive Electron Affinities

If the electron affinity of an element is negative, it means that energy is released when the electron is added to the neutral atom, making the anion more stable. On the other hand, if the electron affinity is positive, it means that energy is absorbed when the electron is attached to the atom, making the formed anion less stable than the neutral atom.

Relate Electron Affinity to Stability of Anions

The larger the negative electron affinity value of an element, the more energy is released when the electron is attached to the neutral atom, and hence, the more stable is the anion of that element. This indicates that the anion is more stable than the neutral atom.

Answering the Exercise

So, if the electron affinity for an element is a negative number, it means that the anion of the element is indeed more stable than the neutral atom because energy is released in the process of the anion formation. This energy release contributes to the stability of the anion compared to the neutral atom.

Key concepts

Anion Stability

An ions or anions are atoms that have gained extra electrons, resulting in a negative charge. When considering anion stability, one must understand how stable these ions are compared to their neutral atom counterparts.

Anions become more stable when the added electron fits well into the existing electronic configuration of the atom. This often involves the electron occupying a low energy state, causing the overall energy of the anion to decrease.

• If a large amount of energy is released when an electron is added, the anion becomes more stable.
• The stronger the electrostatic attraction between the nucleus and the added electron, the more stable the anion.

The concept of stability is directly linked to how much energy is released upon the formation of the anion, and this release of energy is often referenced when discussing electron affinity.

Energy Release

When an electron is added to a neutral atom, energy can either be released or absorbed. This process determines the electron affinity of the atom.

Energy release signifies a stabilizing effect, as the system is losing energy and moving to a more stable state. This indication shows that the newly formed anion has a lower energy level compared to when it was a neutral atom.

• A negative electron affinity means energy is released, enhancing the stability of the anion.
• In contrast, if energy is absorbed, this suggests a less stable anion, as it indicates an uphill energetic process.

The concept of energy release is crucial as it represents the core principle behind why certain atoms prefer to gain electrons and become anions.

Gaseous Atom

In the context of electron affinity, we often refer to gaseous atoms. This is because, in this state, atoms experience minimal interaction with other atoms, allowing for an ideal examination of electron interactions.

The gaseous state provides a clear picture of how a solitary atom will interact with an incoming electron.

• In a gaseous state, electron affinity measurements are more accurate since they are unaffected by intermolecular forces.
• The term "isolated" highlights the fact that the atom is not bonded to any other atoms, focusing solely on its intrinsic properties.

Understanding gaseous atoms is essential for getting an accurate depiction of electron affinity values as they pertain to individual elements.

Negative Electron Affinity

Negative electron affinity refers to the phenomenon where an atom releases energy upon gaining an electron. This negative value indicates a favorable reaction, where the formation of the anion is preferred due to the resultant energy release.

A negative value is important as it signifies the level of attraction between the added electron and the nucleus.

• Elements with highly negative electron affinities readily accept electrons, forming more stable anions.
• This behavior can be observed in halogens like chlorine and fluorine, which have highly negative electron affinities.

In summary, negative electron affinity effectively explains why some elements more readily acquire additional electrons, underscoring their tendencies to form stable anions.