Atomic Structure and Periodicity

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Electron Configurations for Potassium Through Krypton

Slide 39

The Orbitals Being Filled for Elements in Various Parts of the Periodic Table

Slide 40

The Periodic Table With Atomic Symbols, Atomic

Numbers, and Partial Electron Configurations

Slide 41

Broad Periodic Table Classifications

Representative Elements (main group): filling s and p orbitals (Na, Al, Ne, O)

Transition Elements: filling d orbitals (Fe, Co, Ni)

Lanthanide and Actinide Series (inner transition elements): filling 4f and 5f orbitals (Eu, Am, Es)

Slide 42

The Order in which the Orbitals Fill in Polyelectronic Atoms

Slide 43

Ionization Energy

The quantity of energy required to remove an electron from the gaseous atom or ion.

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

where, the atom or ion is assumed to be in its ground state.

Slide 44

Periodic Trends

First ionization energy:

increases from left to right across a period;

decreases going down a group.

Slide 45

The Values of First Ionization Energy for

The Elements in the First Six Periods

Slide 46

Trends in Ionization Energies

for the Representative Elements

Slide 47

Electron Affinity

The energy change associated with the addition of an electron to a gaseous atom.

X(g) + e  X(g)

These values tend to be exothermic (energy released). Adding an electron to an atom causes it to give off energy. So the value for electron affinity will carry a negative sign.

Slide 48

The Electronic Affinity Values for Atoms Among the

First 20 Elements that Form Stable, Isolated X- Ions

Slide 49

Periodic Trends

Atomic Radii: Atomic radii can be obtained by measuring the distances between atoms in chemical compounds and atomic radius is assumed to be half this distance.

Decrease going from left to right across a period. This decrease can be explained in terms of the increasing effective nuclear charge in going from left to right. The valence electron are drawn closer to the nucleus, decreasing the size of the atom.