Periodic Behavior

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Slide 1

Periodic Trends

Slide 2

Atomic Radius

Definition: Half of the distance between nuclei in covalently bonded diatomic molecule

Radius decreases across a period

Increased effective nuclear charge due to decreased shielding

Radius increases down a group

Each row on the periodic table adds a “shell” or energy level to the atom

Slide 3

Table of Atomic Radii

Slide 4

Period Trend: Atomic Radius

Slide 5

Ionization Energy

Increases for successive electrons taken from the same atom

Tends to increase across a period

Electrons in the same quantum level do not shield as effectively as electrons in inner levels

Irregularities at half filled and filled sublevels due to extra repulsion of electrons paired in orbitals, making them easier to remove

Tends to decrease down a group

Outer electrons are farther from the nucleus and easier to remove

Definition: the energy required to remove an electron from an atom

Slide 6

Ionization Energy: the energy required to remove an electron from an atom

Increases for successive electrons taken from the same atom

Tends to increase across a period

Electrons in the same quantum level do not shield as effectively as electrons in inner levels

Irregularities at half filled and filled sublevels due to extra repulsion of electrons paired in orbitals, making them easier to remove

Tends to decrease down a group

Outer electrons are farther from the nucleus

Slide 7

Table of 1st Ionization Energies

Slide 8

Periodic Trend: Ionization Energy

Slide 9

Electron Affinity

Affinity tends to increase across a period

Affinity tends to decrease as you go down in a period

Electrons farther from the nucleus experience less nuclear attraction

Some irregularities due to repulsive forces in the relatively small p orbitals

Definition - the energy change associated with the addition of an electron

Slide 10

Periodic Trend: Electron Affinity

Slide 11

Electronegativity