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DRAWING LEWIS DOT STRUCTURES
Drawing a simple electron-dot structure
Drawing electron-dot structures is easiest if you follow the simple steps that are outlined below, using hydroxylamine, NH2OH, as an example.
1. Write out a simple structural diagram of the molecule in order to clearly show which atom is connected to which.
If you are not sure of the bond connectivity, the structures of other similar molecules can often provide a useful clue. Thus if you know that ammonia, NH3, has nitrogen as its central atom, then you might recognize that hydroxylamine is just a derivative of ammonia in which one of the hydrogen's has been replaced with a hydroxyl group:
It's also useful to know that the atoms hydrogen, nitrogen and oxygen are commonly connected to 1, 3, and 2 other atoms, respectively. The simple molecules for which electron-dot structures are drawn can often be thought of as consisting of one or more "central" atoms to which other atoms are attached.
The points outlined above will become part of your "chemical intuition" as you develop more experience in writing out structures from molecular formulas.
2. Draw electron-dot structures of the individual atoms in the molecule.
What you are doing here is showing how many valence electrons each atom contributes to the structure. We see that the total number of valence electrons is 14.
3. Bring the atoms together in a way that places eight electrons around each atom wherever possible.
Of the 14 valence electrons, 8 are needed to form the four covalent bonds in hydroxylamine, leaving six to be distributed as lone pairs. Placing these on the nitrogen and oxygen atoms as shown yields a structure conforming to the octet rule.
Electron-dot structures of ions
Ions are treated in basically the same way as neutral species, the only complication being that the number of electrons must be adjusted to account for the net electric
