Lewis Structures and Bonding Theories

Flashcards for reviewing lecture notes on Lewis Structures, Electronegativity, Electron Affinity, Formal Charge, Resonance, and VSEPR Theory.

Representing Covalent Compounds

Representation of covalent compounds using chemical formulas and Lewis structures.

Electronegativity

A measure of an atom's ability to attract shared electrons in a chemical bond.

Electron Affinity

The amount of energy released (or absorbed) when an atom gains an electron in the gas phase to form a negative ion.

Electronegativity (What it measures)

Attraction for shared electrons in bonds.

Electron Affinity (What it measures)

Energy change when gaining 1 electron (gas phase).

Electronegativity (Type of value)

Relative (no units).

Electron Affinity (Type of value)

Absolute (measured in kJ/mol).

Electronegativity (When it applies)

In bonded atoms.

Electron Affinity (When it applies)

For isolated gaseous atoms.

Step 1 for Drawing Lewis Structures

Count the total number of valence electrons from the compound's formula.

Step 2 for Drawing Lewis Structures

Determine the central atom (least electronegative) and connect to other elements with single bonds.

Step 3 for Drawing Lewis Structures

Distribute any remaining electrons on outer atoms then central atoms until octets are achieved or all electrons are used.

Step 4 for Drawing Lewis Structures

Check if all atoms have octets (8 total electrons) or duets (2 in the case of H); if short, move lone pairs into double/triple bonds.

Formal Charge

A bookkeeping tool to help determine the most likely Lewis structure of a molecule or ion.

Formula for Formal Charge

(Valence electrons) - (Nonbonding electrons) - 1/2(Bonding electrons)

Resonance

Occurs when two or more valid Lewis structures can be drawn for a molecule or ion.

VSEPR Theory

Helps predict the shape of molecules by thinking about how the electrons around a central atom repel each other.

Key Idea of VSEPR

Arrangement of electron groups to be as far apart as possible.

Electron Group

A single bond, a double bond, a triple bond, or a lone pair.