The document discusses ionization energy, which is the minimum energy required to remove an electron from an isolated gaseous atom or ion. It notes that ionization energy increases with each electron removed, and there is a large increase when removing inner shell electrons closer to the nucleus. Ionization energy also follows periodic trends, increasing within rows of the periodic table and decreasing within columns, with smaller atoms tending to have higher ionization energies due to being closer to the nucleus. Electrons are always removed from the highest principal energy level when forming ions.

1. Section 7.4
Ionization Energy
Dan Corney
Anna Erkalova
Frank Muzika
John Yoffee

2. 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

3. 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

4. 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

5. First Ionization Energy Trends

6. 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

7. 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)

8. 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

9. Electron Configuration of Ions
• Electrons are always removed from orbitals
with largest principal quantum number.
• This means that 4s would be removed before
3d

10. 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)

11. 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?

12. 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

13. Answers
• (D) 1s2 2s2 2p6 3s1
• Metals
• [Ar]3d6
• K<Na<P<Ar<Ne
• True

14. Outside the Class