The periodic table

Before you start...

Lecture outline

The link between material properties and microscopic structure is a central theme in chemistry. These lectures use the periodic table to explore the connections between the properties of the elements and their electron configurations.

Quantum numbers and the periodic table

Factors affecting the valence shell

Factors affecting the valence shell. Anything that influences the valence electrons will affect the chemistry of the element.

Factors (in order of decreasing importance) Effect
1.valence principal quantum number n Larger n means a larger valence shell (because n controls the size of orbitals)
2.nuclear charge Z Larger Z means a smaller valence shell (because higher positive charge on the nucleus attracts the valence electrons, and pulls them inward)
3.number of core electrons More core electrons means a larger valence shell (because highly penetrating core electrons repel valence electrons, and push them farther from the nucleus)

Atomic radius

Ionic radius

Ionization energy

Why metals are metals

Explaining elemental properties: the s block elements

The properties of the alkali metals ultimately result from their ns1 valence configuration.

property of alkali metals explanation


very low ionization energy; the electron sea model works well for alkali metals


ns1 valence configuration contributes just 1 electron to the electron sea. The sea is weak. Metal cations aren't tightly bound and it's easy to slide them past each other.

low densities

Alkali metals have the largest radii and lowest atomic weight in each period. Low mass in high volume = low density.

highly reactive

very low ionization energies make alkali metals good electron donors in redox reactions.

General Chemistry Online! The periodic table

Copyright © 1997-2005 by Fred Senese
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Last Revised 07/25/05.URL: