Electron Done Me Wrong: Atoms in a Nutshell

Understanding electricity means first recalling how atoms work. Though you could never tell by looking at them (at least with the naked eye), these atoms are as active as the protagonists of “Desperate Housewives.”

At the core of this basic building block of matter is, of course, a nucleus, comprised (in part) of one or more positively-charged protons. Around these orbit electrons – the negative answer to the proton’s positive disposition. Depending on how many electrons an atom has, it may have one orbit of electrons or several. Hydrogen has a single electron in its one little orbit, while uranium has 92 electrons across seven orbits.

What matters for our purposes, though, is not how big the atom is, but how many electrons are in its outermost (or valence) orbit, in relation to how many it could have there. Nature is pretty specific about the maximum number of electrons it will accommodate in a given orbit. Two is tops for the first orbit, and eight is tops for the second. The third orbital would be full at eight, too (though it could squeeze in twice that many for parties). Let's consider an aluminum atom, for example. It has 13 electrons: two (the maximum) in the first orbit, eight (the maximum) in the second orbit, and the remainder – three – in its third and final orbit, which isn't full (it could fit at least five more).

Generally, the number of protons in an atom equals the number of electrons, and their charges cancel each other out. But such stability is not always the case – what kind of story would we have if it was? If you think of an atom as a family (The Atom Family, if you will) made up of particles, the protons pretty much stay at home. Electrons, however, sometimes behave like the can’t-help-myself bad boys in a maudlin country song: always hooking up with other opposites, or just hitting the road to roam free. In fact, they're often called free electrons.

It’s a story older than – ahem – Atom and Eve: In the right situation, an electron parts company with its home atom, leaving it with bad memories and a net positive charge. Atoms that have such a charge are called ions. We’ve just described a cation (a positively-charged ion), but there are also anions (negatively charged ions, with more electrons than protons).

Some inherently stable materials (wood is an example) are comprised of atoms whose electrons are what you might call the marrying type – they tend to stay put in their shells. These materials are insulators. Due to the particular arrangement of electrons orbiting their nuclei – the outermost orbit is happily full – they are not inclined to accommodate lone electrons cruising the neighborhood. Other materials, however, are more libertine. In them, electrons have the potential to move about easily from one atom to another, or to hit the electron highway. These are conductors. That’s the case with our aluminum atom (and metals in general). One or more of its three free electrons might decide to wander off; likewise, the valence shell has room to accommodate visitors.

All of which brings us back to electricity.

Next Page Fuel of Hard Knocks: Electricity in a Nutshell

1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | Links | Full Article