Electron Gain Enthalpy

Electron Gain Enthalpy

Definition of electron gain enthalpy

Electron gain enthalpy is the energy gained by a gas atom when an electron is accepted to form a negative ion. It is measured in electron volts per atom or kJ per mole (kJ/mol). The easiest method used to determine this energy is the electron gain enthalpy method, which is based on the fact that only the closest electrons are readily available for ionization, and it uses atomic emission spectroscopy.

Electron gain enthalpy describes the strength of an atom to accept extra electrons. The electron present in the atom’s outermost shell gives off energy in this process. The energy released in this process can be released as either kinetic or potential energy. It goes without saying that the higher the kinetic energy, the more unrestrained will be its movement; conversely, if it is potential energy that gets released, then such an atom will not move about too much. If we talk about the energetic nature of an atom, then irrespective of what kind of potential or kinetic energy it is that gets released upon accepting an extra electron, such ways are always preferable and more favourable over others since they ensure negligible disturbance to the well-established stability of the concerned atom.

Electron gain enthalpy is an important parameter in the study of electron capture. It is one of the most interesting and useful techniques used to study in vitro biochemical reactions. It is based on the principle that if an electron has a low energy level, it is more likely to pass its kinetic energy over to other molecules or atoms. It also helps to predict how stable a substance is.

Electron Gain Enthalpy Example

• Negative Electron Gain Enthalpy: “Negative electron gain enthalpy” is a term used to characterize the stability of halogens and the strength with which they bind( gain) electrons. The energy released by this process is recorded in negative values as a measure of the stability that halogens achieve upon gaining additional electrons.
• Positive Electron Gain Enthalpy: Some elements accept more than two electrons(which indicate the valence levels) with much ease due to high electron gain enthalpy. For instance, noble gases are high electron gain elements with a positive electron gain enthalpy. As a result, they show reluctance to accept additional electrons in their valence, shell-leading to highly reactive states.

Factors That Affect Electron Gain Enthalpy

• Nuclear Charge: When the total number of electrons increases, its force of attraction with the nucleus as well as with the newly added electrons increases, leading to an increase in its magnitude of enthalpy.
• Atomic Size: When there is an increase in the number of electrons on an atom, the overall distance between the nucleus and the last electron increases. This decreases the force of attraction between the core and newly added electrons. The net result is that the atom’s overall charge becomes less negative.
• Electronic Configuration: Metals that have only half-filled or whole valence shells are very chemically stable. They tend to perform chemical reactions with the loss of electrons, not the gain of them. Therefore, the electron gain enthalpy of such elements is substantially large in value.

Electron Gain Enthalpy of Halogens 

Electron gain enthalpy of halogens is defined as the amount of energy given to an electron when it moves from a higher energy level to a lower one or is attracted by a proton (H+) or an electron. The energy difference between the two levels, that is the energy that flows as heat when an electron gains this energy, is also given in kJ/mol.

The magnitude of electron gain enthalpy of halogens decreases from iodine (I2 ) to bromine (Br2 ), then increases again from bromine to chlorine (Cl2 ).

In the chemical bonding theory, the shared electron pair is strong and stable in the chemical bonding theory. The chemical bonds are formed by the electrons. The stronger the bond between the two atoms, the stronger their attraction. In other words, the more electronegative elements will have a stronger bond because they are able to attract electrons from other atoms.

In halogens, electron gain enthalpy is negative when they lose an electron. This means that they emit electromagnetic radiation when they lose an electron in order to balance charges. Electron gain enthalpy then becomes positive when halogens gain an electron. When a halogen gains an electron and forms a bond, it is unstable because of the two extra electrons in the outer shell. Halogens then tend to lose one of these electrons to form compounds that are more stable. This can be seen from their electron gain enthalpies which are negative for fluorine (-3,159 kJ/mol), chlorine (-1,811 kJ/mol), bromine (-1,801 kJ/mol), and iodine(-1,677 kJ/mol).

Difference between electron gain enthalpy and electronegativity

Electronegativity (EN) is a measure of how strongly atoms attract electrons. EN is measured on the Pauling scale, from 0 to 4.0; the larger the number, the more attracted electrons are. For example, chlorine has an EN of 3.16 and fluorine has an EN of 3.98. So fluorine attracts electrons more strongly than chlorine does.

The difference between electron gain enthalpy and electronegativity isn’t just a difference in the name; it’s a difference in definition and use. Electronegativity is a property of an element when it is part of a single atom or molecule. Electron gain enthalpy is a property of atoms when they are part of a chemical bond between two atoms.

Electron gain enthalpies are always less than electronegativities because it takes energy to break bonds. That’s true even in reactions where bonds form at the same time as other bonds break.

Conclusion 

In this material, we have discussed the concept of electron gain enthalpy, its examples, and what are the factors affecting electron gain enthalpy, and much more. 

In the chemical bonding theory, the shared electron pair is strong and stable in the chemical bonding theory. The chemical bonds are formed by the electrons. The stronger the bond between the two atoms, the stronger their attraction. In other words, the more electronegative elements will have a stronger bond because they are able to attract electrons from other atoms.