## lowest energy & most stable Lewis structures

BriannaParrington-1B
Posts: 29
Joined: Fri Apr 06, 2018 11:04 am

### lowest energy & most stable Lewis structures

what determines the lowest energy of a Lewis structure? What does it mean when it asks to draw the most stable lewis structure? Does the amount of bonds or lone pairs present in a lewis structure determine the energy or stability?

Rosamari Orduna 1D
Posts: 31
Joined: Fri Apr 06, 2018 11:04 am

### Re: lowest energy & most stable Lewis structures

By calculating the formal charges (using FC = VE - NBE - 1/2BE) for each element we can then see how close the formal charges are to zero. The closer to zero, the more probable the structure. This would be the structure with the lowest energy.

the textbook also say: the formal charge on an atom in a given Lewis structure—the charge it would have if the bonding were perfectly covalent

kendallbottrell
Posts: 31
Joined: Fri Apr 06, 2018 11:02 am

### Re: lowest energy & most stable Lewis structures

To choose the most stable Lewis structure with the lowest energy, calculate the formal charges for all the atoms and choose the molecule that has all of them closest to zero. This ties into resonance structures - for example, if you have charges on one form of -2, +1, -1 and on another form 0,+1,0, the second form would be the most stable and the lowest energy.

Erin Li 1K
Posts: 30
Joined: Fri Apr 06, 2018 11:03 am

### Re: lowest energy & most stable Lewis structures

you would have to calculate the formal charge by the equation:
formal charge = number of valence - lone electrons - (shared electrons/2)

Jordanmarshall
Posts: 16
Joined: Fri Apr 06, 2018 11:03 am

### Re: lowest energy & most stable Lewis structures

one can also calculate the formal charge by:
Formal charge = Valence electrons - # of electrons directly relating to element