The Atomic Universe - Part I

So what makes touch such a potent and compelling force? Where does it derive its intensity and energy from? Now is probably a good time to examine the ‘stuff we are really made of.’

The world inside an atom:

Every cell, tissue and organ of the human body is made up of molecules which in turn are comprised of atoms. An atom is the smallest part of an element that still retains the properties of that element. It consists of other sub-atomic particles – the main three of which are the neutron (neutral) and proton (positively charged particle) that reside in its nucleus and the electron (negatively charged particle) that orbits around the nucleus in a cloud of electrons.

Usually the number of electrons equal the number of protons and the atom has no charge - it is neutral. However, some atoms easily lose an electron leaving the atom with more protons than electrons and therefore inducing a positive charge; other atoms gain an electron leaving behind a negative charge. The loss or gain of electrons is responsible for all chemical reactions and for bonding atoms together. And a group of atoms that are bonded together is called a molecule. Whew!

Atom Bonds!

It is necessary to clearly understand the concept of electron density in order to grasp the workings of an atom. Electron density is the level of concentration of electrons in any particular area in an atom. The electron density is maximum near the nucleus of an atom and diffuses away from it. Inside a single atom this is seen as a field of lines extending between electrons and the nucleus showing the direction of maximum increase of density. Since the density is at a peak near the nucleus, arrays of trajectories end around each nucleus within an atom (as depicted in the diagram).

Therefore, the individual density-indicative trajectories or routes of the many bonding atoms meet at common points between each other; in other words, at points where maximum levels of electron density from different neighbouring atoms intersect. The figure shows common areas where sets of maximum electron density lines from different atoms touch one another; almost blurring boundaries between one atom and the next. This overlap of lines where electron density is highest forms the link between a pair or more of bonding atoms. {Diagram from www.chemistry.mcmaster.ca, used with permission}

Electron density is a measurable property. It not only determines how ‘electronic charge’ is dispersed through real space within an atom and through molecules formed by atoms but also determines the appearance and form of matter. The figure indicates slightly thick lines of maximum electron density linking nuclei of two or more bonded atoms which ascertain the molecular graph; further predicting molecular structure and finally, therefore, the appearance and structure of the entity or object these molecules build. {Diagram from www.chemistry.mcmaster.ca, used with permission}

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