VSEPR and Molecular Geometry

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Covalent Bond Noun

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[koh-vey-luhnt bond]

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Covalent Bond

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A chemical bond formed when two non-metal atoms share one or more pairs of valence electrons to achieve stability.

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Example: Two hydrogen atoms and one oxygen atom share their outer electrons to form stable covalent bonds, creating a water molecule.

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VSEPR Theory Noun

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[ves-per thee-uh-ree]

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VSEPR Theory

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A model that predicts the three-dimensional shape of molecules by minimizing the electrostatic repulsion between valence shell electron pairs.

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Example: This image shows how VSEPR theory predicts different 3D molecular shapes, like linear or tetrahedral, based on the repulsion between electron pairs.

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

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Example: This image shows a methane molecule (CH₄), where the central carbon atom and four hydrogen atoms form a specific 3D shape called a tetrahedral geometry.

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Electron Pair Repulsion Noun

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[ih-lek-tron pair ri-puhl-shuhn]

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Electron Pair Repulsion

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The principle stating that electron pairs in the valence shell of an atom repel each other, arranging themselves to maximize distance.

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Example: This diagram shows how electron pairs in water (H₂O) and carbon dioxide (CO₂) repel each other, forcing the atoms into specific shapes and bond angles.

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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 is not involved in bonding and belongs exclusively to one atom in a molecule.

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Example: This model of a water molecule shows two lone pairs (yellow lobes with dots) on the central oxygen atom, which are pairs of electrons not used 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 is shared between two atoms, creating the covalent bond that holds them together in a molecule.

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Example: This diagram shows that a bonding pair is a pair of electrons shared between two atoms, like the Nitrogen and Hydrogen shown, which holds them together in a chemical bond.

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Bond Angle Noun

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[bond ang-guhl]

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Bond Angle

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The angle formed between two adjacent bonds on the same central atom within a molecule, influencing its overall shape.

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Example: This diagram of a methane molecule shows the bond angle, which is the angle formed between two chemical bonds connected to the same central atom.

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Electronegativity Noun

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[ih-lek-troh-neg-uh-tiv-i-tee]

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Electronegativity

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A chemical property that describes the tendency of an atom to attract a shared pair of electrons towards itself.

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Example: This diagram shows that the difference in electronegativity between atoms determines the type of chemical bond, ranging from nonpolar covalent (small difference) to ionic (large difference).

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Polar-Covalent Bond Noun

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[poh-ler koh-vey-luhnt bond]

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Polar-Covalent Bond

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A type of covalent bond where electrons are shared unequally between two atoms because of a significant electronegativity difference.

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Example: In a water molecule, the oxygen atom pulls electrons more strongly than the hydrogen atoms, creating a polar-covalent bond with slightly charged ends.

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Nonpolar-Covalent Bond Noun

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[non-poh-ler koh-vey-luhnt bond]

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Nonpolar-Covalent Bond

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A type of covalent bond where electrons are shared equally between two atoms due to having similar or identical electronegativity values.

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Example: Two identical oxygen atoms share their outer electrons equally between them, forming a stable nonpolar-covalent bond where neither atom pulls the electrons closer.