Section 3: Hydrogen theory From carbon to hydrogen energy

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Hydrogen Compounds

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Atoms combine by sharing or transferring their electrons (see previous section).

There are three types of bonds:

• Ionic - a loosely bound electron from one atom "transfers" a deeper orbital of another
• Covalent - two electrons are "shared" between the two atoms
• Metallic - crystalline structures

The orbit shells' maximum fillings (completion number) are as follows:

• First shell - two electrons
• Second shell - eight electrons
• Third shell - eighteen electrons

The really stable compounds have a completed number of electrons in the valence shell. In other words, in looking at HCL, the valence shell gets a completed number of 8 electrons in the compound. Chlorine has 7 electrons, and hydrogen shares one - for 8 to be stable.

The oxygen atom

In water, oxygen has 6 valence electrons. The two hydrogen atoms each provide one electron to complete the valence shell of 8. The valence shell is the orbit shell most loosely bound, or the one furthest from the nucleus.

The valence shell (outermost shell) is the only one represented in Lewis notation. This is the oxygen molecule in Lewis notation.

The water molecule The hydrogen nuclei are on top and bottom. The oxygen nucleus is in the middle. This is a simplification. Actually they are more angular. But, the point is, the red valence electrons in this covalent bonding have a full eight electrons in the second shell. The first shell has two electrons, as represented in blue. Actually in the electrons spin around also, creating electro-magnetic waves. These complex movements are based on attractiveness and repulsiveness, making compounds possible.

This is the Lewis diagram for water. This is closer to the actual angular model. Gilbert N. Lewis at the University of California, Berkeley first suggested the desire of each atom to have a full valence shell. When one calculates the quantum mechanics (electron volts), the "full valence" model falls short, but it is a good "approximation." Just as Einstein used a constant for simplification in his equation relating mass and energy. See http://www.madsci.org/posts/archives/dec97/878173513.Ch.q.html for a more detailed discussion of this.

Thus, the reactions to produce hydrogen chloride and water produce very stable compounds. The proclivity to unite the elements is very strong and energy is released in the process.

Oxygen and hydrogen that have been bound to form water can be separated through applying energy in passing an electrical current through the water. This is called electrolysis.

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