Multiple Elements in a Molecule

[Sam McNeill 1E]

When drawing Lewis Structures that have multiple elements, how do you know which go where? For example, problem 2B, where the structure is ONF?

[Brian Tangsombatvisit 1C]

Usually the atom with the lowest ionization energy or lowest electronegativity goes in the center of the atom. This is because this atom is less likely to hold onto its valence electrons tightly and more likely to share its electrons with other atoms. In the case with ONF, Nitrogen should go in the center of the molecule.

After figuring out the center atom, place the other atoms around it and try to balance the total number of valence electrons for the entire molecule, using lone and bonded pairs accordingly. A helpful guideline to remember is the HONC 1234 rule. Oxygen generally makes 2 bonds and nitrogen generally makes 3 bonds. A good rule to remember is that halogens always only make single bonds (fluorine in this case).