Electron+Affinity

Electron Affinities Is energy change when an electron is added to a gaseous atom. It measures the attraction or affinity of the atom to the electron. Almost every atoms release an energy when we added electron to its which make Electron Affinity number is negative. The more negative it is, the more attract to the electron that element is. For some element such as noble gases and Be and Mg the Electron Affinity is positive number because in these element the subshell is already filled so when we added more electron it reach the new subshell so it require more energy. Note that 7A group have a very high(I mean very negative) Electron Affinity.

Electron Affinity It is defined as the energy change that occurs when an electron is added to a gaseous atom

Energy is released for most atoms when an electron is added Ex. Cl(g) + e− → Cl−(g) ΔE = -349 kJ/mol

Generally, electron affinity increases from left to right across the periodic table It remains mostly constant down a group

Above is all by Mr. Williams



Electron Affinity: Electron affinity is the energy required to detach an electron from a negatively charged atom. Ex: X- → X + e- The energy released when an electron is added to an atom is defined by (E(Initial) - E(Final)). The signs that relate to the energy are opposite than the signs related to heat. The energy is positive when energy is released after adding an electron. All elements on the periodic table have positive electron affinities. Anion atoms that are more stable then their neutral form have greater electron affinities. Chlorine has the strongest attraction to electrons and Mercury has the lowest attraction while noble gases are relatively neutral. Electron affinity applies to molecules as well as elements.

Patterns across the table: The pattern of electron affinities across the periodic table of elements are rather randomly distributed. Generally nonmetals have a higher electronic affinity than metals. Generally they increase across the period because of decreasing atomic radius and increasing number of electron. It decreases when going down a group because of the increased atomic radius and the large increases of electrons which greatly lowers stability.



Sources: http://en.wikipedia.org/wiki/Electron_affinity http://www.webelements.com/webelements/properties/media/tables/cylinders/electron-affinity.jpg http://voh.chem.ucla.edu/vohtar/winter00/20A/lec5_files/image006.gif