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Electron Affinity. The energy of the process in which an electron is acquired by the in the gas phase. Usually expressed in . atom . kJ/mol. Definition. As you go down a column, the electron affinity becomes less negative (less energy).
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The energy of the process in which an electron is acquired by the in the gas phase. • Usually expressed in atom kJ/mol. Definition
As you go down a column, the electron affinity becomes less negative (less energy). • Since the atomic radius increases going down the periodic table, the new electrons experience less of an attractive force. • One exception to this rule: fluorine’s electron affinity is lower that chlorine’s. Since the volume of the fluorine atom is much smaller, the strength of electron-electron repulsion is stronger. Coulomb’s law shows that like charges that are in closer proximity of each other will repel to a greater degree. Trend: Column
As you go across a row, the electron affinity becomes more negative (more energy). • The Z* values increases, yielding higher values of electron affinity. • Although the trend is generally true, affinities across the row are quite irregular. • Beryllium or any other element in that column have no electron affinities because of their electron configurations. When one of these elements gain an electron, they must place the new electron in a new subshell. This makes the element very unstable. • Nitrogen has a low electron affinity. When the new electron is added, this will create a pair of electrons in the same orbital. The nitrogen atom will experience significant electron-electron repulsion. *Grumble* *Grumble* Negative *Grumble* *Grumble* Trend: Row
Exceptions exist when the electron’s outer subshell is at exactly half or maximum capacity. • Since the electron is essentially balanced, or stable, it will be unwilling to accept the electron. • As a result, the electron affinity will be lower for elements with s2 or p3 or p6orbitals. Exception, Exception!What’s your function?
