Portfolio_Group_03

=__**Group of Chemists** __ =




MEHWISH AND FARYAL PUT UR PARTS INTO THE CHAPETERS SECTION!! NOT HERE!!!

=__IONIZATION ENERGY__=  A valence-shell electron is promoted from a lower-energy orbital to a higher-energy one with a larger principal quantum number n. If enough energy is absorbed, the electron can be removed completely from the atom, leaving behind an ion. The amount of energy necessary to remove the highest energy electron from an isolated neutral atom in the gaseous state is called the atom’s **ionization energy,** abbreviated **Ei.** The minimum Ei values correspond to the group 1A elements (alkali metals), the maximum Ei values correspond to the group 8A elements (noble gases), and a gradual increase in Ei occurs from left to right across a row of the periodic table-from Na to Ar, for example. One such trend is that ionization energy going down a group in a periodic table from, He to Rn and from Li to Fr, for example. As atomic number increases going down a group, both the principal quantum number of the valence-shell electrons are less tightly held and Ei is smaller. Ionization is not limited to the loss of a single electron from an atom. Two, three, or even more electrons can be lost sequentially from an atom, and the amount of energy associated with each step can be measured. Example: M + Energy à  M+ + e- (first Ei) M + Energy à  M+ + e- (second Ei) M + Energy à  M+ + e- (third Ei) And so forth... It is much harder to remove a negativly charged electron from a positively charged ion than from a neutral atom. = =
 * H + energy **** à ****<span style="FONT-SIZE: 12pt; LINE-HEIGHT: 115%; FONT-FAMILY: 'Times New Roman','serif'"> H + e- **

ELECTRON AFFINITY
Just as it is possible to measure the energy change on removing an electron from an atom to from a cation, it’s also possible to measure the energy change on adding an electron to an atom to from an anion. An element’s electron affinity, abbreviated Eea, is the energy change that occurs when an electron is added to an isolated atom in the gaseous state. Ionization energies are always positive because energy must always be added to remove an electron from an atom. Electron affinities, however, are generally negative because energy is usually released when a neutral atom adds an electron. H (1s1) + e- + energy à H- (1s2) As with ionization energies, electron affinities show a periodicity that is related to the electron configurations of elements. Group 7A elements have the most electron affinities, corresponding to the largest release of energy, while group 2A and group 8A have low electron affinities, corresponding to a small release or even absorption of energy.