Draw complete Lewis structures, including lone pairs, for the following compounds.
(a)
(b)
(c)

Verified step by step guidance

1. Identify the total number of valence electrons for each compound. For pyridine (C5H5N), count the valence electrons from carbon (4 each), hydrogen (1 each), and nitrogen (5).
2. Draw the skeletal structure for pyridine, ensuring that the nitrogen atom is part of the six-membered ring and alternating double bonds are present. Add lone pairs to the nitrogen atom to complete its octet.
3. For pyrrolidine (C4H9N), count the valence electrons from carbon, hydrogen, and nitrogen. Draw a five-membered ring with nitrogen, ensuring that nitrogen has a lone pair and a hydrogen atom attached to it.
4. For furan (C4H4O), count the valence electrons from carbon, hydrogen, and oxygen. Draw a five-membered ring with oxygen, ensuring that oxygen has two lone pairs and alternating double bonds are present in the ring.
5. Check each structure to ensure that all atoms have complete octets (except hydrogen, which should have a duet) and that the total number of valence electrons used matches the number calculated initially.

Key Concepts

Lewis Structures

Lewis structures are diagrams that represent the bonding between atoms of a molecule and the lone pairs of electrons that may exist. They are essential for visualizing the arrangement of electrons in molecules, showing how atoms are bonded and the presence of any lone pairs. This helps in predicting the geometry, reactivity, and properties of the molecule.

Heterocyclic Compounds

Heterocyclic compounds are cyclic compounds that have atoms of at least two different elements as members of their ring(s). In the given question, pyridine, pyrrolidine, and furan are examples of heterocycles containing nitrogen and oxygen atoms. Understanding the role of these heteroatoms is crucial as they influence the electronic structure and reactivity of the compounds.

Lone Pairs and Formal Charge

Lone pairs are pairs of valence electrons that are not shared with another atom and are sometimes represented in Lewis structures. They can affect the shape and reactivity of molecules. Formal charge is a concept used to determine the charge distribution within a molecule, calculated by assuming equal sharing of electrons in bonds. Correctly assigning lone pairs and formal charges is vital for accurate Lewis structures.