Table of Contents
Although there is a slight difference between the two, electron gain enthalpy is sometimes also referred to as electron affinity. The amount of energy released when an electron is added to an isolated gaseous atom is defined as electron gain enthalpy. Energy can be released or absorbed during the addition of an electron.
Overview of Electron Gain Enthalpy
An element’s electron gain enthalpy is the amount of energy produced when a neutral isolated gaseous atom absorbs an extra electron to create a gaseous negative ion or anion. It is represented by the symbol ∆egH. The greater the amount of energy released in the preceding process, the greater the element’s electron gain enthalpy. An element’s electron gain enthalpy is a measurement of the firmness or strength with which an extra electron is bound to it. It is expressed in electron volts per atom or kilojoules per mole. When an electron is added to an atom, the reaction can be endothermic or exothermic. It also describes the strength of the extra electron that becomes attached to the gaseous atom. The greater the amount of energy released in the chemical reaction, the greater the electron gains enthalpy of the element. Such reactions can be exothermic or endothermic in nature, releasing or absorbing energy depending on the constituent elements.
X(g)+e– X–(g)
Negative Electron Gain Enthalpy:
As energy is released, the halogen atoms gain stability by gaining electrons, which is represented by its negative values. Because halogens have a strong affinity for the stable, noble gas state, they have a higher negative electron gain enthalpy.
Positive Electron Gain Enthalpy:
The energy required to enter an electron into an atom is defined as a positive electron gain enthalpy. This is the process by which an element shows a reluctance to accept a new electron (generally the second atom). Because noble gases have a high positive electron gain enthalpy, the extra gained electron is placed in the higher maximum energy levels, resulting in a highly reactive and unstable electronic configuration. The atoms become negatively charged as a result of the addition of one electron, and thus the addition of the next electron is frequently disrupted by electrostatic repulsion. Such reactions necessitate an additional supply of energy, resulting in a positive electron gain enthalpy of the second electron in nature.
The positive electron gain enthalpy has an exciting feature in that it becomes more negative as it moves from left to right in a period as opposed to coming from top to bottom in a group. In general, the variation of positive gain enthalpy is erratic within a group or over time. The atoms become negatively charged as a result of the addition of one electron, and thus the addition of the next electron is frequently disrupted by electrostatic repulsion. Such reactions necessitate an additional supply of energy, resulting in a positive electron gain enthalpy of the second electron in nature.
Define electron gain enthalpy
Electron gain enthalpy is sometimes referred to as electron affinity, despite the fact that there is a tiny difference between the two. Electron gain enthalpy is the amount of energy released when an electron is added to an isolated gaseous atom. With the addition of an electron, energy can be released or absorbed. The enthalpy of electron gain is measured in kJ/mol.
Electron gain enthalpy of halogens
Because of the small size of the F atom, the electron-electron repulsions in the compact 2p subshell are strong, and thus the incoming electron is not accepted as easily as it is with Cl (less electron-electron repulsions). As a result, chlorine’s electron gain enthalpy is lower than that of fluorine. The amount of energy released when an electron is added to an isolated gaseous atom is defined as electron gain enthalpy. The electron gain enthalpy of F is less negative than that of Cl due to electron-electron repulsion in a small-sized F atom. Because of the increase in atomic size as we move down the group, the electron gain enthalpy becomes less negative.
The electron gain enthalpy decreases as one moves down a group due to an increase in atomic size. However, due to electron-electron repulsion in small-sized F atoms, the electron gain enthalpy of F is less negative than that of Cl. As a result, the correct sequence is F>CL>Br>I.
Difference between electron gain enthalpy and electronegativity
In different states of atoms, electronegativity and electron gain enthalpy are different (free as in element or bound as in compound). The tendency of an element’s atom in a chemical compound to attract a shared pair of electrons towards it in a covalent bond is defined as electronegativity. There are several electronegativity scales present. These include the Pauling scale, the Milliken-Jaffe scale, and the Allred Rochow scale, among others. The Pauling scale is the most commonly used of these, with fluorine (the most electronegative element) arbitrarily assigned a value of 4.0.
The enthalpy shift that occurs when a neutral gaseous atom accepts an extra electron to create an anion is known as electron gain enthalpy. The tendency of an isolated gaseous atom to take an extra electron and form a negative ion is known as electron gain enthalpy. The tendency of an element’s atom in a chemical compound to draw a shared pair of electrons towards it in a covalent bond is known as electronegativity. Electronegativity is a criterion for quality. It isn’t anything that can be measured. The electron gain enthalpy, on the other hand, is a quantitative metric. It’s a quantifiable quantity.
Electron gain enthalpy is the energy produced when a neutral isolated gaseous atom receives an extra electron to form the gaseous negative ion or anion. It can be represented by ∆egH. The greater the amount of energy released in the preceding process, the greater the element’s electron gain enthalpy. Electron gain enthalpy is the enthalpy change associated with an isolated gaseous atom (X) when it gains an electron to form its equivalent anion.
FAQs
Explain why the electron gain enthalpies of some second-period elements, such as O and F, are less negative than those of the third-period elements.
The elements of the second period have the smallest atomic size of any element in their group. As a result of the significant electron-electron repulsions within the atom, the additional electron is not accepted with the same ease as the remaining elements in the same group.
What is the definition of positive electron gain enthalpy?
The energy required to enter an electron into an atom is defined as a positive electron gain enthalpy. In general, the variation of positive gain enthalpy is erratic within a group or over time.
