Sunday, January 10, 2010

You Can't Touch an Atom

There is something that everything we can touch and feel has in common: Everything is made of atoms. Atoms are composed of three particles: Protons, neutrons, and electrons. And they are very tiny; a million of them could be placed side by side across the width of a human hair.

There are millions of different substances, or types of matter. But, in nature, there are only 92 varieties of atoms. Atoms of one kind make up an element, so there are 92 natural elements. Every substance of matter is made up of one or more of these elements.

The lightest element is hydrogen with only one proton and one electron. The heaviest is uranium, which has 92 protons and electrons and typically 146 neutrons.

The weird thing about an atom is that none of them ever come into physical contact with each other. That is because every atomic nucleus, which is the central part of an atom containing nearly all of the atom’s mass, is surrounded by negatively-charged electrons.

They orbit the nucleus, in which reside positively-charged protons and neutral neutrons. Neutrons act as a sort of nuclear glue that keeps the positively-charged protons from repelling each other. Like charges repel and unlike charges attract, so the electrons are kept orbiting the nucleus in regions of space called electron clouds. But because of the repulsive nature of their electric charges, they never touch each other. They also never touch electrons of neighboring atoms.

The upshot of this is that even though you pick up an object, like a pencil, the atoms of your fingers are never really in contact with the atoms of the pencil. Rather, the force you feel when you touch, or even strike an object is caused by the electrical repulsion of billions of electron clouds surrounding the atoms in your finger and in the object you are touching.

Although this is an interesting fact of science, it probably wouldn’t work as a defense in a court of law. “But your honor, my client technically never touched the defendant!” But some lawyer somewhere probably has tried it, if he knows his chemistry.


Jason McKnight said...

I considered this thought for a while when I was a child. It is good to know my hypothesis was correct.

Brayton Rogers said...

This is cool, but what is friction?

Adam Van Antwerp said...

Friction is also caused by IMF's (intermolecular forces). Whereas some IMF's (such as the repulsive force described above) are just that, repulsive, there are others that are attractive, such as Van Der Whaals forces. These are the attractive forces that are responsible for keeping a gecko on a wall. When two particles exists close to each other, they tend to want to stay next to each other because of momentary polarization, due to the unpredictable nature of electrons, causing an attraction.

Unknown said...
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Ted Newman said...

The repulsion still plays a part when you talk about surface roughness. When two rough surfaces rub together, they act just like you'd expect. They function as though they're touching, but on the atomic level, they're never actually colliding. The molecular attraction is a separate phenomenon that also adds to the effects of friction along with surface roughness. Simple explanation here.