Electronic Configuration

Topic 12 ATOMIC STRUCTURE: Electronic configuration

12. 1. Ionization energy

If an electron obtains enough energy it jumps beyond the highest energy level and becomes a free electron: the atom itself becomes a positive ion.
This electron transition is represented as follows: n = 1 to n = (. Notation n = ( refers to the “world” outside the atom – beyond the control of the nucleus; any electron outside an atom has no potential energy (energy = 0).
With hydrogen the ionization energy can be calculated from the frequency at the point in the emission spectrum where the lines in the Lyman series converge. (see extension in topic 2 notes)

(http://www.physchem.co.za/Atomic/Hydrogen%20Spectrum.htm: shows energy levels)

There are different types of ionization energies:

first ionization energy (IE1):

2. the minimum energy needed to remove one (first/highest energy level)/most loosely held electron electron from 1 mole of gaseous (or free/by itself) atoms to make a gaseous cations;

X (g) (( X+ (g) + e-

3. the more strongly the electron is attracted to the nucleus, the greater the amount of energy needed 4. ionization energy is usually measured in kilojoules per mole Kj mol-1 of atoms; 5. ionization energies are positive values (endothermic process) as energy is needed to remove an electron.

successive ionization energy:

• energy needed to remove second, third,... electrons from 1 mole of gaseous ions, e.g.

second ionization energy (IE2) X+ (g) (( X2+ (g) + e-

third ionization energy (IE3): X2+ (g) (( X3+ (g) + e-

7. the lower the energy level an electron is on, the closer it is to the nucleus, the more strongly it is attracted, the more energy is needed;

8. in the same atom, successive ionization energies increase as a result of a combination of the following factors:

9. the electron-electron