Question

Why are the electron affinities of beryllium and magnesium is almost zero ?? Give five reason?

Answer 1

Beryllium is a chemical element with atomic number 4 and the symbol Be. It's a steel-gray alkaline earth metal that's strong, light, and brittle. It is a divalent element that only occurs in nature in the form of minerals when combined with other elements. Magnesium (Mg) is a chemical element with the atomic number 12 and the symbol Mg. It's a gleaming grey solid that looks a lot like the other five elements in the periodic table's second column (group 2, or alkaline earth metals).

Complete answer:
The amount of energy released when an electron is connected to a neutral atom or molecule in the gaseous state to produce a negative ion is described as the electron affinity (${{E}_{ea}}$) of an atom or molecule.
$X\left( g \right)\text{ }+\text{ }{{e}^{-}}~\to \text{ }{{X}^{-}}\left( g \right)\text{ }+\text{ }energy$
This is not to be confused with the enthalpy change of electron capture ionisation, which is negative when energy is released. In other words, there is a negative difference between this enthalpy change and the electron affinity.
The electron affinity for a surface is defined differently in solid state physics.
Nonmetals, on average, have a higher positive (${{E}_{ea}}$) than metals. Atoms with more stable anions than neutral atoms have a higher (${{E}_{ea}}$). Chlorine draws additional electrons the most strongly, whereas neon attracts them the least. Prior to reaching group 18, (${{E}_{ea}}$) tends to grow over time in the periodic table. This is due to the atom's valence shell filling; when a group 17 atom gains an electron, it releases more energy than a group 1 atom because it receives a filled valence shell and is therefore more stable. The valence shell is complete in group 18, thus any additional electrons are unstable and tend to be expelled soon.
Be and Mg have completely filled $\left[ He \right]2{{s}^{2}}$and $\left[ Ne \right]3{{s}^{2}}$ configurations, respectively.
The 2s and 3s orbitals have reached their maximum capacity and do not require any further electrons to achieve stability. Because they desire to shed one electron to go to the nearest noble gas configuration, Be and Mg are unable to absorb electrons.

Note:
The alkaline earth metals are a set of six chemical elements in the periodic table's group 2. Beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra) are the elements involved (Ra). At normal temperature and pressure, the elements have extremely similar properties: they are all lustrous, silvery-white, and slightly reactive metals. They (together with helium) share a complete outer s-orbital structurally; that is, this orbital includes its full complement of two electrons, which the alkaline earth metals quickly lose to form cations with charge +2 and oxidation state +2.