CHEMICAL BONDING ANALOGIES
... from ScienceAnalogies.com
Coordinate covalent or dative bonding is often described in a simple
fashion by saying that it involves one atom donating or giving a pair of
electrons to another, so that this bonding partner can have a full outer
shell. When electrons are counted up in an electronic dot diagram, this
coordinate covalent pair is counted with each of the atoms. It is similar
to borrowing a pair of books from the public library ... the books are
given to you and you treat them essentially as if they belonged to you;
yet at the same time the books are counted as being part of the library
collection.
Source: Original
A nonpolar covalent bond forms when electrons are shared equally
between atoms. A polar covalent bond forms when electrons are not shared
equally ... the more electronegative atom "gets" more electrons than he
gives away by sharing. A coordinate covalent bond is imagined to form when
one atom donates the entire pair of electrons which are shared with the
other atom.
A restaurant analogy for these situations could be as follows:
A nonpolar covalent bond is formed if you give your friend half of your
cheeseburger in exchange for half of his chicken burger. A polar covalent
bond would be like your friend taking all of your cheeseburger and in
exchange giving you just a small bite of his chicken burger. A coordinate
covalent bond forms if you notice a homeless person outside, bring them
into the restaurant, and give them your whole dinner to eat.
Source: Original
The actual electronic structure of a molecule or ion which involves
resonance is often explained by saying that it is the average of several
contributing electronic structures which are drawn so as to show the
double bond in several different locations in the species. In order to
remind students that the actual resonance hybrid structure doesn't
alternate from one contributing structure to another from time to time,
but rather has its own special structure all the time, it is convenient to
use the analogy that a resonance hybrid is like a mule . When you look at
a mule ( which is a cross between a horse and a donkey) you don't see a
donkey at one time and a horse at another... you see a mule at all times.
Source: Sienko, M. J. and Plane, R. A. Chemistry
Toronto: McGraw-Hill, 1964 p.94
From this Analogies page you can go either to the
other analogy pages:
[ Atomic Structure | Biology
| Chemical Bonding | Chemical
Reactions]
[Electrolytes | Equilibrium
| Matter ]
... or the main page of ScienceAnalogies.com
© Copyright 1997 - 2012
