Sunday, January 23, 2011

Molecular geometries that you see everyday!

Everyday items may indeed have shapes similar to the molecular geometries of certain covalent compounds.  Below are some examples:

There are several "linear" objects that we can see in a single day.  A pencil, for example - or even your body when standing straight up.

"Bent" geometries are a bit harder to find.  I noticed that my lamp, which has adjustable joints, can form a stick-and-ball model of a "bent" molecular geometry.

One of the most difficult to find, in my opinion, would definitely have been the "trigonal pyramidal."  I noticed that a foldable stool illustrates the idea of three bonds and one lone pair quite nicely.

If you go driving, you may notice a Mercedes on the streets.  This is where I found an example of the "trigonal planar" geometry.  The logo itself is drawn via connecting the vertices of a triangle inscribed in a circle.

Finally, a "tetrahedrally" shaped item can be easily located by any photographer.  One of their main tools, the tripod, forms this shape almost perfectly.  In fact, when the tripod is un-extended, it could fall under the trigonal pyramidal category.


Linear Geometry Picture:


Bent Geometry Picture:


Trigonal Pyramidal Picture:

Foldable stool:

Trigonal Planar Picture:

Mercedes Logo:

Tetrahedral Picture:


An Electron-ic Poem

How and why we're shared
To minimize repulsion
And form the octet

Why are covalent bonds formed, you may ask?  Since atoms aim to have the electron configuration like those of the most stable noble gases, said atoms must attain eight valence electrons (except for hydrogen, which only needs two).  By sharing electrons with other atoms (in other words, forming a covalent bond), the atoms can make their orbitals overlap so as to have the eight valence electrons.  The minimization of repulsion is evident in the different molecular geometries that covalent compounds emulate.  For example, in a tetrahedral form (4 bonded pairs, no lone pairs [on the central atom]), the bonded atoms each move 109.5ยบ away from another, ensuring the least amount of repulsion from the electrons possible.  In essence, this haiku states two of the main principles of behavior that are followed by electrons when a covalent compound is formed.