Molecular Polarity Basics Quiz

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Questions and Answers

What are the steps for predicting molecular polarity?

  • Determine if the compound is molecular
  • Check if the molecule has polar covalent bonds
  • Assess if polar covalent bonds are arranged asymmetrically
  • All of the above (correct)

What two factors do polarity depend on?

Symmetry and Bond Polarity

Non polar molecules have positive and negative sides.

False (B)

A symmetrical molecule is always non polar.

<p>True (A)</p> Signup and view all the answers

Molecules with no shared electrons are called?

<p>Non Polar</p> Signup and view all the answers

Bent molecules are always polar.

<p>True (A)</p> Signup and view all the answers

What is the shape of a trigonal planar molecule?

<p>Always Polar</p> Signup and view all the answers

Can a molecule be asymmetrical if the shape is the same but one atom is different?

<p>Yes</p> Signup and view all the answers

What is VSEPR?

<p>Valence Shell Electron Pair Repulsion Theory</p> Signup and view all the answers

What are VSEPR groups used for?

<p>Used to predict molecular geometry</p> Signup and view all the answers

What does molecular geometry depend on?

<p>The number of electron groups around the atom</p> Signup and view all the answers

Molecules with 2 VSEPR electron groups are identified as?

<p>Linear</p> Signup and view all the answers

Molecules with 3 VSEPR electron groups are known as?

<p>Trigonal planar</p> Signup and view all the answers

Molecules with 4 VSEPR electron groups can be?

<p>Tetrahedral or bent</p> Signup and view all the answers

What is the electron domain geometry for 0:3?

<p>Trigonal planar</p> Signup and view all the answers

What is the electron domain geometry for 0:4?

<p>Tetrahedral</p> Signup and view all the answers

What is the electron domain geometry for 1:3?

<p>Trigonal pyramid</p> Signup and view all the answers

What is the electron domain geometry for 2:2?

<p>Bent</p> Signup and view all the answers

What is the electron domain geometry for 0:2?

<p>Linear</p> Signup and view all the answers

Flashcards

Molecular Polarity

Describes whether a molecule has a distinct positive and negative end due to uneven electron distribution.

Molecular Compound

A molecule composed entirely of nonmetals, where electrons are shared between atoms.

Polar Covalent Bond

A bond between atoms with significantly different electronegativity, leading to uneven electron sharing.

Non-Polar Covalent Bond

A bond where electrons are shared equally between atoms with similar electronegativity.

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Molecular Geometry

The shape of a molecule, determined by the arrangement of atoms and electron pairs.

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VSEPR Theory

Predicts molecular shapes by considering the repulsion between electron pairs in the valence shell of a central atom.

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Non-Polar Molecule

A molecule with a symmetrical arrangement of atoms and electron pairs, resulting in no net dipole moment.

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Polar Molecule

A molecule with an asymmetrical arrangement of atoms and electron pairs, resulting in a net dipole moment.

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Linear Geometry

A molecule with two electron groups, resulting in a 180-degree bond angle.

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Trigonal Planar Geometry

A molecule with three electron groups, resulting in approximately 120-degree bond angles.

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Tetrahedral Geometry

A molecule with four electron groups, resulting in 109.5-degree bond angles.

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Trigonal Pyramidal Geometry

A molecule with three electron groups and one lone pair, resulting in a shape like a pyramid.

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Bent Geometry

A molecule with two electron groups and two lone pairs, resulting in a bent or V-shape.

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Electronegativity

The ability of an atom to attract electrons in a chemical bond.

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Dipole Moment

Represents the separation of positive and negative charges in a polar molecule.

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Hydrocarbon

A molecule composed only of carbon and hydrogen atoms, always non-polar.

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Electron Groups

The number of electron groups around a central atom in VSEPR theory.

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Lone Pair

A pair of electrons that are not involved in bonding.

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Bond Angle

The angles between bonds in a molecule, influenced by VSEPR theory.

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Study Notes

Molecular Polarity Basics

  • Molecular polarity is determined by bond polarity and molecular symmetry.
  • A molecule is classified as molecular if it is composed only of nonmetals and involves shared electrons.

Steps for Predicting Molecular Polarity

  • Check if the molecule contains polar covalent bonds.
  • If polar bonds are present, assess their arrangement: asymmetry indicates polarity, while symmetry results in non-polarness.

Characteristics of Polar and Non-Polar Molecules

  • Polar molecules exhibit partial positive and negative charges due to uneven electron sharing.
  • Non-polar molecules lack distinct charged sides and can be symmetrical or have no shared electrons.
  • Molecules with only carbon and hydrogen are inherently non-polar.

Molecular Geometry and Polarity

  • Bent and trigonal pyramidal molecular shapes are always polar due to asymmetry.
  • Trigonal planar and tetrahedral structures can be polar or non-polar depending on symmetry.
  • Linear geometries can also be polar or non-polar based on symmetrical arrangements.

VSEPR Theory

  • VSEPR (Valence Shell Electron Pair Repulsion) Theory predicts molecular shapes based on electron group arrangements.
  • The geometries depend on the number of electron groups around the central atom, influencing bond angles.

Specific Molecular Geometries

  • Linear Geometry: 2 VSEPR electron groups, 180° angles, non-polar or polar depending on symmetry.
  • Trigonal Planar: 3 VSEPR groups, ~120° angles, polar or non-polar based on bond arrangement.
  • Tetrahedral: 4 VSEPR groups, 109.5° angles, can yield bent or trigonal pyramidal shapes based on lone pair presence.
  • Bent Geometry: Always asymmetrical, thus inherently polar.

Electron Group Arrangements

  • 0 : 3 VSEPR groups results in a trigonal planar molecular geometry.
  • 0 : 4 results in a tetrahedral molecular geometry.
  • 1 : 3 yields a trigonal pyramidal shape.
  • 2 : 2 creates a bent structure in a tetrahedral electron domain.

Key Takeaways

  • Always assess shape symmetry and bond polarity to determine molecular polarity.
  • The arrangement of electrons and atoms greatly affects molecular characteristics and behaviors.

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