Explain Why The Addition Of An Electron To A Chlorine Atom Is An Exothermic Process And The Addition Of An Electron To A Magnesium Atom Is An Endothermic Processs
The addition of an electron to an atom is an exothermic or endothermic process because it involves a change in the energy of the system. In this case, we are looking at the addition of an electron to chlorine and magnesium atoms.
When an electron is added to a chlorine atom, it enters the outermost energy level known as the valence shell. Chlorine already has seven valence electrons, and it requires only one additional electron to complete its octet (having eight valence electrons), which is a stable electron configuration. The addition of this electron releases energy because the electron is attracted to the positively charged nucleus of the chlorine atom. The energy released during this process makes it exothermic.
On the other hand, when an electron is added to a magnesium atom, it enters the third energy level. Magnesium has two valence electrons, and adding an electron to it would give it a stable configuration of a filled second energy level, as well as a half-filled third energy level. However, adding an electron to magnesium requires energy because there is a repulsion between the negatively charged extra electron and the existing electrons in the atom. Therefore, the addition of an electron to a magnesium atom is an endothermic process.
In summary, the addition of an electron to a chlorine atom is an exothermic process because it releases energy, while the addition of an electron to a magnesium atom is an endothermic process because it requires energy.