Electronic structure

How are carbon atoms in a straight chain represented in bond-line notation?

In a zigzag pattern

How should bonds in a molecule with a double bond be drawn?

As far apart as possible, typically 120°

Does the direction of a single bond matter when drawing skeletal structures?

No

Which atoms must always be explicitly drawn in skeletal structures

Heteroatoms

Which hydrogen atoms must explicitly be drawn in skeletal structures?

Hydrogen atoms attached to heteroatoms

Are lone pairs required to be drawn in skeletal structures?

No; their inclusion is optional

What is the maximum number of bonds a carbon atom can have?

Four

What is the first step in calculating formal charge?

Determine the atom’s appropriate number of valence electrons

What is the second step in calculating formal charge?

Determine how many electrons the atom actually exhibits/has in the structure

What does it mean when a charge is delocalized?

The charge is shared among two or more atoms

What generally happens to stability when electrons are delocalized?

The molecule or ion is stabilized

What should you avoid breaking when drawing resonance structures?

Sigma bonds

What is the restriction for second-row elements in resonance structures?

Electrons cannot exceed an octet

What must be included visually for resonance structures to be complete?

Formal charges

What resonance pair involves a lone pair adjacent to a pi bond?

Allylic lone pair

What resonance pattern involves a carbocation adjacent to a pi bond?

Allylic carbocation

What resonance pattern results in a carbon double bonding?

Lone pair next to a carbocation

What resonance pattern involves electronegativity?

Pi bond next to atoms of differing electronegativity

What resonance pattern involves a ring?

Conjugated pi bonds

What is the first major criterion for determining the importance of a resonance structure?

Greatest number of filled octets

How does the number of formal charges affect resonance-form importance?

Fewer formal charges generally makes a resonance form more significant

Where is a negative charge preferably located?

On a more electronegative element

What orbital must a lone pair occupy to participate in resonance?

A p orbital

Can a lone pair on an sp²-hybridized atom participate in resonance if that atom already has a pi bond?

No

C-H bond IR range/characteristics

3600-2700 cm^-1

Alcohol IR range/characteristics

3200-3600 cm^-1, broad/symmetrical

Triple bond IR spectra range/characteristics

2700-1900 cm^-1, weak in symmetrical alkynes

Double bond IR spectra range/characteristics

1900-1500 cm^-1

Single bond IR spectra range

1500-500 cm^-1