This is so because the second electron has to be forced to enter the mono negative ion. For some elements, however, this is not the case. The second (reverse) definition is that electron affinity is the energy required to remove an electron from a singly charged gaseous negative ion. This is measured by the energy released when an element in its gaseous state accepts an electron to form an anion. The observed periodic trends in electron affinity are that electron affinity will generally become more negative, moving from left to right across a period, and that there is no real corresponding trend in electron affinity moving down a group in the periodic table. the same as the atomic radius trend but opposite the ionization energy trendd. As the principal quantum number increases, the size of the orbital increases and the affinity for the electron is less. Suppose A is an atom, A + e- A- + X KJ/mole X is the electron affinity of A. There are two trends for electron affinity. Cl (g) + e-→Cl-(g) For most atoms, this is a negative quantity - or energy is released. What is electron affinity? So, going across the periodic table, that is, from the left hand side to the right hand side the trend in electron affinity increases as the elements on the right hand side are able to accept the extra electron. As a result, when an electron is added to an atom it can cause some atoms to become highly unstable. Definition of electron affinity Electron affinity is the affinity of an element to an electron. In simple words, electron affinity is the tendency of an atom to accept the electron. While ionization energy is the energy change incurred from losing an electron, electron affinity is the energy change incurred from gaining an electron. The electron affinity trend is:a. the same as the ionization energy trend and the atomic radius trendb. So this is an exothermic reaction. the same as the ionization energy trend but opposite the atomic radius trendc. The actual charge felt by the valence electron is known as effective nuclear charge (Z*) and is given by ... [Explained] Trends of Electron Affinity In The Periodic Table. the opposite of the ionization energy trend and atomic radius trend Now I’ll tell you about the Electron affinity trend in the periodic table. The electron affinity (E ea) of a neutral atom or molecule is defined as the amount of energy released when an electron is added to it to form a negative ion, as demonstrated by the following equation: [latex]X(g) + e^- \rightarrow X^{-}(g)[/latex] Electron affinity is measured for atoms and molecules in the gaseous state only, since in the solid or liquid states their energy levels would … Actually there are many factors which affect the electron affinity, but to make it simple and easy to remember, I’ll explain … Electron affinity is the energy change when an electron is added to an atom to form an anion (negatively charged ion). Trends: As with ionization energy, there are two rules that govern the periodic trends of electron affinities: Electron affinity becomes less negative down a group. First, as the energy that is released by adding an electron to an isolated gaseous atom. Electron affinity can be defined in two equivalent ways. Electron affinity decreases moving down a column and increases moving left to right across a row of the periodic table. The first electron affinity is always exothermic that is negative the second electron affinity of the same element will be positive or endothermic. Generally, electrons tend to repel one another. (An unbound electron has an energy of zero.) They are expressed in KJ mol-1. The electron affinity cannot be determined directly but is obtained indirectly from the Born-Haber cycle. November 23, 2020. Electron affinity is opposite to ionisation process, i.e., when an atom accepts an electron it is called electron affinity. Electron affinity is how easily an atom accepts an electron.