01 Structure and Bonding in Organic Molecules Free Online FlashCards

What are valence electrons?

Valence electrons are the electrons in an atom’s outer shell; they participate in bonding.

How do single, double, and triple covalent bonds differ?

A single bond shares one electron pair, a double bond shares two, and a triple bond shares three.

What $\sigma$ and $\pi$ bonds make up double and triple bonds?

A double bond contains one $\sigma$ bond and one $\pi$ bond; a triple bond contains one $\sigma$ bond and two $\pi$ bonds.

What does a molecular formula leave unspecified?

A molecular formula gives the number of each type of atom, but does not show how those atoms are connected.

How are carbon atoms represented in a skeletal formula?

In a skeletal formula, each line end and vertex represents a carbon. Carbon-bound hydrogens are usually omitted.

What geometry is associated with $sp^3$ hybridization?

Four electron-density regions commonly correspond to $sp^3$ hybridization and a tetrahedral arrangement, with bond angles of about $109.5^\circ$.

How does an $sp^2$ carbon form a $\pi$ bond?

An $sp^2$ atom has three hybrid orbitals in a plane; its remaining unhybridized $p$ orbital can form a $\pi$ bond.

What geometry is associated with $sp$ hybridization?

Two electron-density regions commonly correspond to $sp$ hybridization and a linear arrangement. Two $p$ orbitals remain available for $\pi$ bonding.

What makes a covalent bond polar?

A bond is polar when its atoms attract shared electrons unequally, commonly because they differ in electronegativity. The more electronegative atom is partially negative.

Why does linear carbon dioxide have no net dipole?

The two polar $\mathrm{C=O}$ bond dipoles in linear carbon dioxide point oppositely and cancel, so the molecule has no net dipole.

What changes between resonance forms?

Resonance forms are alternative electron-bookkeeping drawings with the same atom positions but different placements of electrons or formal charges.

What is the relationship between a molecule and its resonance forms?

A molecule is a resonance hybrid with delocalized electrons; it does not switch back and forth between resonance drawings.