Writing Lewis Structures for Covalent Compounds

• Write the correct skeletal structure for the molecule (continued).

Remember two guidelines.

• First, hydrogen atoms will always be terminal. Since hydrogen requires only a duet, it will never be a central atom because central atoms must be able to form at least two bonds and hydrogen can form only one.
• Second, many molecules tend to be symmetrical, so when a molecule contains several atoms of the same type, these tend to be in terminal positions.
• This second guideline has many exceptions. In cases where the skeletal structure is unclear, the correct skeletal structure is usually provided.