Lewis Structures

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Valence Electrons Noun

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[vay-lence i-lek-trons]

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Valence Electrons

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The electrons in the highest occupied energy level of an atom, which are involved in forming chemical bonds with other atoms.

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Example: This Bohr model of a Sodium atom shows its electrons arranged in shells. The single electron in the outermost shell is its valence electron.

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Octet Rule Noun

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[ok-tet rool]

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Octet Rule

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The principle that atoms tend to bond in such a way that they each have eight electrons in their valence shell.

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Example: An oxygen atom shares electrons with two hydrogen atoms to get a full and stable outer shell of eight electrons, which is the octet rule.

Front

Lewis Electron-Dot Structure Noun

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[loo-is i-lek-tron dot struk-cher]

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Lewis Electron-Dot Structure

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A diagram showing the bonding between atoms and the lone pairs of electrons that may exist within a molecule.

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Example: This diagram shows a water molecule (H₂O). Dots represent valence electrons, which are shared between oxygen and hydrogen atoms to form stable chemical bonds.

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Structural Formula Noun

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[struk-cher-ul for-myuh-luh]

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Structural Formula

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A formula that uses letter symbols and bonds to show the relative positions of atoms within a given molecule.

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Example: This image shows how a structural formula uses lines for bonds and dots for electrons to represent the arrangement of atoms in molecules like water.

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Molecular Geometry Noun

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[muh-lek-yuh-ler jee-om-i-tree]

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Molecular Geometry

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The three-dimensional arrangement of the atoms that constitute a molecule, which determines many of its chemical and physical properties.

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Example: This image shows the 3D shape of a methane molecule (CH₄), an example of tetrahedral molecular geometry, which results from its underlying Lewis structure.

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Formal Charge Noun

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[for-mul charj]

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Formal Charge

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The hypothetical charge assigned to an atom in a molecule, assuming that electrons in all chemical bonds are shared equally.

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Example: This image demonstrates how to calculate the formal charge for the central atom in five different molecules by applying the formula FC = VE - NBE - B.

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Molecular Polarity Noun

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[muh-lek-yuh-ler poh-lar-i-tee]

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Molecular Polarity

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A separation of electric charge leading to a molecule having a net dipole moment due to its geometry and bonds.

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Example: In a water molecule, the oxygen atom pulls electrons more strongly, giving it a slight negative charge (δ-), while the hydrogen atoms get a slight positive charge (δ+), creating a polar molecule.

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Lone Pair Noun

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[lohn pair]

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Lone Pair

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A pair of valence electrons that are not shared with another atom in a covalent bond and belong to one atom.

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Example: This image shows a water molecule. The two yellow lobes on the central oxygen atom represent lone pairs, which are pairs of electrons not involved in bonding.

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Bonding Pair Noun

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[bon-ding pair]

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Bonding Pair

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A pair of electrons that are shared between two atoms, forming a covalent bond that holds the atoms together.

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Example: This Lewis structure shows a bonding pair as two electrons (blue dots) shared between the central nitrogen atom and a hydrogen atom, forming a covalent bond.

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Single Bond Noun

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[sing-guhl bond]

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Single Bond

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A covalent bond in which one pair of electrons is shared between two atoms, represented by a single solid line.

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Example: This animation shows two atoms (crosses) each sharing one electron (dot) to form a single pair of shared electrons between them, creating a single bond.