Chemical Bonding: Ionic, Covalent, and Metallic Models

Manual: General · Subject: Chemistry

Explain how atoms bond and how bonding models connect structure to properties.

Why atoms bond

Bonding and stability

Atoms bond to reach lower-energy arrangements. Ionic bonding involves electron transfer and electrostatic attraction, covalent bonding involves electron sharing, and metallic bonding features a lattice of cations immersed in a delocalized electron sea.

Major bond types

Ionic

Usually metal + nonmetal
Electron transfer
High melting points and brittle crystals

Covalent

Usually nonmetal + nonmetal
Electron sharing
Can form molecules or network solids

Lewis structures

Lewis structures help count valence electrons and visualize bonding pairs and lone pairs. Formal charge can be estimated by $\text{FC} = V - N - \tfrac12 B$ where $V$ is valence electrons, $N$ is nonbonding electrons, and $B$ is bonding electrons.

Constructing a Lewis structure

1

Step 1: Count total valence electrons, adjusting for charge.
2

Step 2: Choose a central atom, usually the least electronegative except hydrogen.
3

Step 3: Connect atoms with single bonds and complete octets where needed.
4

Step 4: Add multiple bonds if the central atom lacks an octet or if formal charges improve.

Which statement best describes metallic bonding?

Electrons are transferred from metal to nonmetal Electrons are shared in pairs between two atoms Positive metal ions are held together by delocalized electrons Atoms bond only after forming ions in solution

What is the main purpose of a Lewis structure?

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Model limitation

Lewis structures are useful but simplified; they do not fully describe resonance, bond order, or molecular shape.

In most stable Lewis structures, formal charges should generally be

as large as possible as close to zero as possible all positive all negative

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