Overview• Ionization energy – the minimum energy required to remove an electron from the ground state of the isolated gaseous atom or ion.• Variations in Successive Ionization Energies• Periodic Trends in First Ionization Energies• Electron Configurations of Ions• Applications outside of class
Ionization Energy Variations • Increases with each electron – More energy require to remove an electron from a more positive ion • Removing inner shell electrons causes GREAT increases in energy – Inner shells are much closer to the nucleus • Large increase always exists when taking from Noble Gas Core
Ionization Energy Variations Interesting Facts • The table on the previous slide does a wonderful job showing ionization energies throughout one row in the periodic table • The large increase of the inner shell supports the idea that only electrons outside the noble gas core are involved in reactions
First Ionization Energy Trends • Within Rows, I increases with Atomic Number • Within Groups, I decreases with Atomic Number • Representative Elements show a larger range of values of I
First Ionization Energy Trends • Smaller Atoms tend to have Higher Energies – Closer to nucleus – Minor irregularities due to • Electron repulsion (Nitrogen to Oxygen) • Electron Shielding (Beryllium to Boron)
First Ionization Energy Trends Interesting Facts • Same factors that influence atomic size also influence atomic energies. • Depends on both the effective nuclear charge and average distance of the electron from the nucleus
Electron Configuration of Ions • Electrons are always removed from orbitals with largest principal quantum number. • This means that 4s would be removed before 3d
Electron Configuration of Ions Interesting Facts • When electrons are added to an atom to form an anion, they are added to empty or partially filled orbital with the lowest available value of n. • Ex. • F (1s22s22p5) F- (1s22s22p6)
Questions• By looking at following electronic configuration of elements, can you predict which element has the lowest first ionization energy? -(A) 1s2 2s2 2p6 (B) 1s2 2s2 2p4 (C) 1s2 2s2 2p6 3s2 (D) 1s2 2s2 2p6 3s1 (E) 1s2 2s2 2p5• Low first ionization energy is considered a property of Metals or Non-Metals?
Questions• Write the Electron Configuration for Co3+.• Arrange the following atoms in order of increasing first ionization energy. Ne, Na, P, Ar, K.• Ionization energy is the ability to capture an electron. -True/False
Outside the Class• Ionization energy has been applied to the atoms of a doorknob when on a dry day you get zapped by a spark. The dry air has transferred electrons onto the doorknob, called field ionization. The extra electrons are then released when you touch the doorknob.
Outside the Class• In the upper atmosphere, photoionization transfers electrons from atoms by using photons from ultraviolet lights. This can cause small molecules such as O2 and N2 to ionize and become O-2 and N-3.