Tag: Sodium

Last time we started our discussion about sodium, and tonight we shall continue it.  We have pretty much covered the quantum mechanical part and the properties and uses of elemental sodium, so tonight we shall focus on some of the compounds of that element.

Sodium compounds are extremely common and widespread, but not universally distributed.  This is important for reasons to be seen later.

The most common sodium compound is common salt, or sodium chloride, NaCl.  Everyone has personal experience with salt, both as a nutrient and as a melting aid for icy surfaces.

Sodium, element number 11, is one of the most common elements in the crust of the earth.  Except for school laboratory demonstrations, few people have ever seen elemental (metallic) sodium because it is so reactive and actually has very limited consumer uses (that would be about zero consumer uses).

We have hinted at the concept of periodicity previously, like last week when we saw how similar the chemical behavior of helium and neon are.  The similarities betwixt hydrogen and lithium are much less marked than those betwixt lithium and sodium, mostly due to the extreme low mass of hydrogen, making quantum effects more pronounced.  Thus, sodium is the second alkali metal after lithium even though hydrogen is in the same column in the periodic table.

In other words, the two first row elements, hydrogen and helium, are aberrant because of their low masses AND because they have only the K electron shell in the ground state AND as a corollary, only the 1s orbital that is filled with only two electrons.  Starting with the second row, the L shell begins to be filled and it contains, in addition to the 1s orbital, a 2s and three 2p orbitals.  Row three elements, sodium being the first of which, also contain in addition to those orbitals, a 3s and three 3p orbitals, making them more like the second row than the second is to the first row.