Chemistry Chapter 6: Chemical Bonding
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Questions and Answers

A chemical bond between atoms results from the attraction between the valence electrons and _______ of different atoms.

nuclei

What does a covalent bond consist of?

a shared electron pair

If two covalently bonded atoms are identical, how is the bond identified?

nonpolar covalent

What is a covalent bond in which there is an unequal attraction for the shared electrons?

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

Atoms with a strong attraction for the electrons they share with another atom exhibit what characteristic?

<p>high electronegativity</p> Signup and view all the answers

What type of bonds possess between 5% and 50% ionic character?

<p>polar covalent</p> Signup and view all the answers

What happens to the percentage of ionic character as the electronegativity difference between two atoms increases?

<p>the greater the bond's percentage of ionic character</p> Signup and view all the answers

What are the electrons involved in the formation of a chemical bond called?

<p>valence electrons</p> Signup and view all the answers

What is a chemical bond that results from the electrostatic attraction between positive and negative ions called?

<p>ionic bond</p> Signup and view all the answers

If electrons involved in bonding spend most of the time closer to one atom rather than the other, what type of bond is it?

<p>polar covalent</p> Signup and view all the answers

If a bond has more than 50% ionic character, what is it called?

<p>ionic bond</p> Signup and view all the answers

A bond characterized by more than 50% ionic character occurs when the electronegativity difference between the two atoms is greater than _______.

<p>1.7</p> Signup and view all the answers

Give an example of a nonpolar covalent compound.

<p>H2</p> Signup and view all the answers

Provide an example of a polar covalent compound.

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

What is an example of an ionic compound?

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

Describe how a covalent bond holds two atoms together.

<p>A pair of electrons is attracted to both nuclei of the two atoms bonded together.</p> Signup and view all the answers

What property of the two atoms in a covalent bond determines whether the bond will be polar?

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

How can electronegativity be used to distinguish between an ionic bond and a covalent bond?

<p>The difference between the electronegativity of the two atoms in a bond will determine whether the bond is ionic or covalent. If the difference in electronegativity is greater than 1.7, the bond is considered ionic.</p> Signup and view all the answers

Describe the electron distribution in a polar covalent bond and its effects on the partial charges of the compound.

<p>The electron density is greater around the more electronegative atom, giving that part of the compound a partial negative charge, while the other part has an equal partial positive charge.</p> Signup and view all the answers

Use the concept of potential energy to describe how a covalent bond forms between two atoms.

<p>As the atoms involved in the formation of a covalent bond approach each other, the electron-proton attraction is stronger than the electron-electron and proton-proton repulsions. The atoms are drawn to each other and their potential energy decreases. Eventually, a distance is reached at which the repulsion has the like charges equal to the attraction of the opposite charges. At this point, potential energy is at a minimum, and a stable molecular form is achieved.</p> Signup and view all the answers

Name two elements that form compounds that can be exceptions to the octet rule.

<p>Hydrogen, Boron, Beryllium, Phosphorus, Sulfur, and Xenon</p> Signup and view all the answers

Explain why resonance structures are used instead of Lewis structures to correctly model certain molecules.

<p>Resonance structures show that one Lewis structure cannot correctly represent the location of the electrons in a bond. Resonance structures depict delocalized electrons, while Lewis structures illustrate electrons in a definite location.</p> Signup and view all the answers

Identify the major assumption of the VSEPR theory, which is used to predict the shape of atoms.

<p>Pairs of valence electrons repel one another.</p> Signup and view all the answers

In water, two hydrogen atoms are bonded to one oxygen atom. Why isn't water a linear molecule?

<p>The electron pairs that are not involved in bonding also take up space, creating a tetrahedron of electron pairs and making the water molecule angular or bent.</p> Signup and view all the answers

What orbitals combine together to form sp3 hybrid orbitals around a carbon atom?

<p>The s orbital and all three p orbitals from the second electron energy level.</p> Signup and view all the answers

What two factors determine whether or not a molecule is polar?

<p>Electronegativity difference and molecular geometry or unshared electron pairs.</p> Signup and view all the answers

How are dipole-dipole attractions, London dispersion forces, and hydrogen bonding similar?

<p>They're all forces of attraction between molecules, where there's an attraction between the slightly negatively charged portion of one molecule and the slightly positively charged portion of another molecule.</p> Signup and view all the answers

Is H-F nonpolar covalent, polar covalent, or ionic?

<p>polar covalent</p> Signup and view all the answers

Is Na-Cl nonpolar covalent, polar covalent, or ionic?

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

Is H-O nonpolar covalent, polar covalent, or ionic?

<p>polar covalent</p> Signup and view all the answers

Is H-H nonpolar covalent, polar covalent, or ionic?

<p>nonpolar covalent</p> Signup and view all the answers

Is H-C nonpolar covalent, polar covalent, or ionic?

<p>polar covalent</p> Signup and view all the answers

Is H-N nonpolar covalent, polar covalent, or ionic?

<p>polar covalent</p> Signup and view all the answers

How is a hydrogen bond different from an ionic or covalent bond?

<p>A hydrogen bond is a dipole-dipole attraction between a partially positive hydrogen atom and the unshared electron pair of a strongly electronegative atom such as O, N, or F. Unlike ionic or covalent bonds, in which electrons are given up or shared, the hydrogen bond is a weaker attraction. Hydrogen bonds are generally intermolecular, while ionic and covalent bonds occur between ions or atoms respectively.</p> Signup and view all the answers

H2S and H2O have similar structures, and their central atoms belong to the same group. Yet H2S is a gas at room temperature, and H2O is a liquid. Use bonding principles to explain why this is.

<p>Oxygen has higher electronegativity than sulfur, creating a highly polar bond. The increased polarity in H2O bonds results in stronger intermolecular forces, making water a liquid at room temperature, while H2S lacks such bonding interactions.</p> Signup and view all the answers

In what way is a polar covalent bond similar to an ionic bond?

<p>There's a difference between the electronegativity of the two atoms in both types of bonds that results in electrons being more closely associated with the more electronegative atom.</p> Signup and view all the answers

Is H2S polar or nonpolar?

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

Is COCl2 polar or nonpolar?

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

Is PCl3 polar or nonpolar?

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

Is CH2O polar or nonpolar?

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

Study Notes

Chemical Bonding Overview

  • Chemical bonds form due to attraction between valence electrons and nuclei of different atoms.
  • Valence electrons are crucial in bond formation.

Types of Chemical Bonds

  • Covalent Bond: Formed by a shared electron pair between atoms.
  • Nonpolar Covalent Bond: Occurs between identical atoms with equal sharing of electrons.
  • Polar Covalent Bond: Unequal attraction for shared electrons leads to partial charges.
  • Ionic Bond: Formed through electrostatic attraction between positive and negative ions.

Electronegativity

  • High electronegativity indicates strong attraction for electrons in a bond.
  • Differences in electronegativity determine bond type:
    • Less than 1.7 indicates covalent bond.
    • Greater than 1.7 indicates ionic bond.

Characteristics of Bonds

  • Bonds with 5% to 50% ionic character are polar covalent.
  • Greater electronegativity difference correlates with increased ionic character.

Examples of Bonds

  • Nonpolar Covalent Compound Example: H2
  • Polar Covalent Compound Example: HCl
  • Ionic Compound Example: NaCl

Bonding Mechanics

  • Covalent bonds hold two atoms through shared electron attraction towards both nuclei.
  • Electron distribution in polar covalent bonds results in partial positive and negative charges on the molecule.

Resonance and Structure

  • Resonance structures illustrate delocalized electrons, unlike fixed positions in Lewis structures.
  • VSEPR theory states that pairs of valence electrons repel, affecting molecule shape.

Molecular Geometry & Polarity

  • Water's non-linear shape results from non-bonding electron pairs creating a tetrahedral arrangement.
  • Factors determining molecular polarity include electronegativity difference and molecular geometry.

Intermolecular Forces

  • Dipole-dipole attractions, London dispersion forces, and hydrogen bonding all represent intermolecular attractions based on charge differences within molecules.
  • Hydrogen bonds are distinct from ionic and covalent bonds as they are weaker and involve interactions between polar molecules.

State of Matter Comparisons

  • H2S is a gas due to weaker intermolecular forces, while H2O is a liquid due to stronger hydrogen bonding from higher electronegativity of oxygen.

Summary of Polar and Nonpolar Bonds

  • Polar covalent bonds have unequal sharing of electrons, leading to partial charges.
  • Nonpolar covalent bonds feature equal sharing, resulting in no charges.
  • Various compounds (like H2S, COCl2, PCl3, CH2O) exhibit different polarities based on their molecular structure and electronegativity differences.

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Test your knowledge of chemical bonding with this review quiz. Explore key concepts like covalent bonds, nonpolar covalent bonds, and the role of valence electrons. Perfect for reinforcing your understanding of Chapter 6 in chemistry.

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