Write equations to demonstrate the difference between electron affinity and the reverse of ionization potential.
Answers
Electron affinity:- It is the energy released or needed for an atom to add a electron.
Ionization energy:- It is the energy required to pull an electron from an atom.
Answer:
Electron affinity is the amount of energy released when a neutral atom or a molecule (in the gaseous phase) gains an electron from outside. This electron addition causes the formation of a negatively charged chemical species. This can be represented by symbols as follows.
X + e– → X– + energy
he addition of an electron to a neutral atom or a molecule releases energy. This is called an exothermic reaction. This reaction results in a negative ion. But if another electron is going to be added to this negative ion, energy should be given in order to proceed with that reaction. This is because the incoming electron is repelled by the other electrons. This phenomenon is called an endothermic reaction.
Therefore, the first electron affinities are negative values and the second electron affinity values of the same species are positive values.
First Electron Affinity: X(g) + e– → X(g)–
Second Electron Affinity: X (g)– + e– → X (g)-2
Electron affinity shows periodic variation in the periodic table. This is because the incoming electron is added to the outermost orbital of an atom. The elements of the periodic table are arranged according to the ascending order of their atomic number. When the atomic number increases, the number of electrons they have in their outermost orbitals increases.
In general, electron affinity should increase along the period from left to right because the number of electrons increases along a period; thus, it is difficult to add a new electron. When experimentally analyzed, the electron affinity values show a zig-zag pattern rather than a pattern that shows a gradual increase.
What is Ionization Energy
Ionization energy is the amount of energy needed by a gaseous atom in order to remove an electron from its outermost orbital. This is called the ionization energy because the atom gets a positive charge after the removal of an electron and becomes a positively charged ion. Each and every chemical element has a specific ionization energy value since atoms of one element are different from atoms of another element. For example, the first and second ionization energies describe the amount of energy required by an atom to remove one electron and another electron, respectively.
First Ionization Energy
First ionization energy is the amount of energy required by a gaseous, neutral atom to remove its outermost electron. This outermost electron is located in the outermost orbital of an atom. Therefore, this electron has the highest energy among other electrons of that atom. Hence, the first ionization energy is the energy required to discharge the highest energy electron from an atom. This reaction is essentially an endothermic reaction.
This concept is associated with a neutrally charged atom since neutrally charged atoms are composed only of the original number of electrons that the element should be composed of. However, the energy required for this purpose depends on the type of element. If all electrons are paired in an atom, it requires a higher energy. If there is an unpaired electron, it requires a lower energy. However, the value also depends on some other facts. For example, if the atomic radius is high, a low amount of energy is required since the outermost electron is located far from the nucleus. Then the attraction force between this electron and the nucleus is low. Therefore, it can easily be removed. But if the atomic radius is low, then the electron is highly attracted to the nucleus and it is hard to remove the electron from the atom.
Second Ionization Energy
Second ionization energy can be defined as the amount of energy required to remove an outermost electron from a gaseous, positively charged atom. Removal of an electron from a neutrally charged atom results in a positive charge. This is because there aren’t enough electrons to neutralize the positive charge of the nucleus. Removing another electron from this positively charged atom will require a very high energy. This amount of energy is called the second ionization energy.
Second ionization energy is always a higher value than the first ionization energy since it is very difficult to remove an electron from a positively charged atom than from a neutrally charged atom; this is because the rest of the electrons are highly attracted by the nucleus after removing one electron from a neutral atom.
Similarities Between Electron Affinity and Ionization Energy
Both are energy-related terms.
The value of both electron affinity and ionization energy depends on the electron configuration of the subjected atom.
Both show a pattern in the periodic table.
Difference Between Electron Affinity and Ionization Energy
Definition
Electron Affinity: Electron affinity is the amount of energy released when a neutral atom or molecule (in the gaseous phase) gains an electron from outside.
Ionization Energy: Ionization energy is the amount of energy needed by a gaseous atom in order to remove an electron from its outermost orbital.