Molecular Shapes

Front

VSEPR Model Noun

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[ves-per mod-l]

Back

VSEPR Model

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A model used to determine molecular geometry by minimizing the repulsion of electron pairs around a central atom.

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Example: This image shows how the VSEPR model predicts different molecular shapes; water (H₂O) is bent while carbon dioxide (CO₂) is linear due to electron arrangements.

Front

Molecular Geometry Noun

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

Back

Molecular Geometry

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The three-dimensional arrangement of atoms within a molecule, which is also commonly referred to as its overall shape.

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Example: This image shows a water molecule (H₂O), where the atoms are arranged in a specific 'bent' shape. This 3D arrangement is its molecular geometry.

Front

Bond Angle Noun

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[bond ang-guhl]

Back

Bond Angle

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The angle formed between two terminal atoms and the central atom in a molecule, defining its geometric structure.

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Example: This diagram shows that a bond angle is the angle formed between three connected atoms, specifically between two hydrogen-carbon-hydrogen bonds in a molecule.

Front

Hybridization Noun

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[hahy-brid-i-zey-shuhn]

Back

Hybridization

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The process where atomic orbitals mix to form a new set of identical hybrid orbitals with equivalent energy levels.

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Example: This diagram shows how different atomic orbitals (electron paths) can mix, or hybridize, to form new, identical orbitals that determine a molecule's shape.

Front

Hybrid Orbital Noun

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[hahy-brid awr-bi-tl]

Back

Hybrid Orbital

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An orbital formed by combining two or more atomic orbitals, which helps explain the observed shapes of molecules.

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Example: This image shows how hybrid orbitals, which are mixed atomic orbitals, arrange themselves in a tetrahedral shape around a central atom with a 109.5° angle.

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Lone Pair Noun

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[lohn pair]

Back

Lone Pair

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An unshared pair of valence electrons not involved in bonding that influences a molecule's shape through repulsion.

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Example: This image shows a water molecule, where the yellow lobes represent lone pairs—electrons on the oxygen atom not involved in bonding, which push the hydrogen atoms into a bent shape.

Front

Sigma (σ) Bond Noun

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[sig-muh bond]

Back

Sigma (σ) Bond

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A covalent bond formed by the direct, head-on overlap of atomic or hybrid orbitals along the internuclear axis.

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Example: This diagram shows two spherical 's orbitals' from different atoms overlapping head-on to form a strong covalent bond, which is called a sigma (σ) bond.

Front

Pi (π) Bond Noun

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[pahy bond]

Back

Pi (π) Bond

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A covalent bond formed by the sideways overlap of unhybridized p orbitals, found in double and triple bonds.

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Example: This diagram shows two p atomic orbitals overlapping sideways to form one pi-bonding molecular orbital, which is the basis of a pi (π) bond.

Front

Linear Shape Noun

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[lin-ee-er sheyp]

Back

Linear Shape

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A molecular geometry where atoms are arranged in a straight line, resulting in a bond angle of 180 degrees.

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Example: This image shows a molecule where the atoms are arranged in a straight line, which is called a linear shape.

Front

Trigonal Planar Shape Noun

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[trig-uh-nl pley-ner sheyp]

Back

Trigonal Planar Shape

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A molecular geometry with a central atom bonded to three other atoms, all lying in a single flat plane.

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Example: This diagram shows a central atom (A) bonded to three other atoms (B), all lying on a flat plane with 120° angles between them.