Covalent Bonding Concepts
50 Questions
7 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What happens when two non-metal atoms react together to form a covalent bond?

  • They share electrons. (correct)
  • They completely transfer electrons.
  • They lose all their valence electrons.
  • They exchange electrons.
  • Chlorine atoms are stable in their isolated form.

    False (B)

    What is the process by which atoms achieve stable outer shells in covalent bonding?

    Sharing electrons

    In a Lewis structure, unpaired electrons are represented by a ______.

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

    Match the chemical species with their corresponding charges:

    <p>H3O+ = Hydronium ion NH4+ = Ammonium ion Cl2 = Chlorine molecule H2 = Hydrogen molecule</p> Signup and view all the answers

    What is the main characteristic of covalent bonds regarding energy?

    <p>Energy is released during bond formation. (C)</p> Signup and view all the answers

    The octet rule states that atoms are stable when they have eight electrons in their outer shell.

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

    What is the significance of valence electrons in chemical reactions?

    <p>They determine the chemical behavior of the element.</p> Signup and view all the answers

    What is the primary feature of delocalized electrons?

    <p>They are not associated with a single atom or one covalent bond. (A)</p> Signup and view all the answers

    All resonance structures of the nitrate ion NO3- have different bond lengths.

    <p>False (B)</p> Signup and view all the answers

    What is the true structure of a molecule that is represented by multiple resonance structures?

    <p>resonance hybrid</p> Signup and view all the answers

    The scenario where there are too many valence electrons is called __________.

    <p>expanded octet</p> Signup and view all the answers

    Match the following exceptions to the Octet Rule with their descriptions:

    <p>Incomplete Octet = Too few valence electrons present Expanded Octet = Too many valence electrons present Odd Number of Electrons = Uneven distribution of valence electrons</p> Signup and view all the answers

    Which of the following best describes the nitrate ion?

    <p>Has bonds that are all of equal length (B), Has one double bond and two single bonds (D)</p> Signup and view all the answers

    Boron in BH3 has a complete octet.

    <p>False (B)</p> Signup and view all the answers

    What must be minimized when determining the most likely resonance structure?

    <p>formal charges</p> Signup and view all the answers

    What is the molecular shape of water (H2O)?

    <p>Bent or V-shaped (D)</p> Signup and view all the answers

    Pi bonds are stronger than sigma bonds.

    <p>False (B)</p> Signup and view all the answers

    What type of bond has electron density symmetrical about a line joining the nuclei?

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

    A molecule with 4 bonding pairs and 0 lone pairs has a ______ geometry.

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

    Match the following molecules with their molecular shapes:

    <p>BeH2 = Linear NH3 = Trigonal pyramidal SO2 = Bent PCl5 = Trigonal bipyramidal</p> Signup and view all the answers

    Which molecule is polar?

    <p>SO2 (B)</p> Signup and view all the answers

    All tetrahedral molecules are nonpolar.

    <p>False (B)</p> Signup and view all the answers

    What is the molecular shape of borane (BH3)?

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

    What happens to bond strength as more electrons are shared?

    <p>Bond strength increases (D)</p> Signup and view all the answers

    A coordinate bond involves the contribution of bonding electrons from two different atoms.

    <p>False (B)</p> Signup and view all the answers

    What prefix is used to indicate two atoms of an element in a molecular naming convention?

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

    The bond length is __________ as the bond strength increases.

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

    Which of the following is an example of a compound with a dative bond?

    <p>BF3 (D)</p> Signup and view all the answers

    Match the following prefixes with their corresponding number:

    <p>mono = 1 di = 2 tri = 3 tetra = 4</p> Signup and view all the answers

    What is the representation used for a coordinate bond in a diagram?

    <p>an arrow</p> Signup and view all the answers

    Ionic substances typically use prefixes in their names.

    <p>False (B)</p> Signup and view all the answers

    What is the electron domain geometry for a molecule with 4 electron pairs?

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

    A molecule with 3 bonding electron domains and 1 lone electron pair has a triangular planar shape.

    <p>False (B)</p> Signup and view all the answers

    How many degrees are the bond angles in a tetrahedral molecule?

    <p>109.5</p> Signup and view all the answers

    A molecule with 2 electron domains has a ______ shape.

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

    Match the number of electron domains with their corresponding geometry:

    <p>2 = Linear 3 = Trigonal Planar 4 = Tetrahedral 5 = Trigonal Bipyramidal 6 = Octahedral</p> Signup and view all the answers

    Which of the following shapes is observed in a molecule with 5 bonding electron domains?

    <p>Trigonal Bipyramidal (D)</p> Signup and view all the answers

    Lone pairs always increase bond angles in molecular geometry.

    <p>False (B)</p> Signup and view all the answers

    What shape results from 4 electron pairs where 1 is a lone pair?

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

    For a molecule with 6 electron domains, the geometry is ______.

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

    Match each shape to the corresponding electron domain arrangement:

    <p>Linear = 2 electron domains Trigonal Planar = 3 electron domains Tetrahedral = 4 electron domains Octahedral = 6 electron domains</p> Signup and view all the answers

    What defines a covalent bond?

    <p>The sharing of electrons between atoms (A)</p> Signup and view all the answers

    A single covalent bond involves the sharing of four electrons.

    <p>False (B)</p> Signup and view all the answers

    What is electronegativity?

    <p>The measure of the force of attraction of an atom towards the electrons in a bond.</p> Signup and view all the answers

    The shape of water (H2O) is described as _______.

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

    Match the following types of bonds with their correct descriptions:

    <p>Single bond = Two electrons shared Double bond = Four electrons shared Triple bond = Six electrons shared Dative bond = One atom donates a pair of electrons</p> Signup and view all the answers

    Which of the following molecules has a trigonal planar shape?

    <p>BF3 (D)</p> Signup and view all the answers

    Resonance structures indicate that a molecule has two distinct types of bonding.

    <p>False (B)</p> Signup and view all the answers

    Define a polar covalent bond.

    <p>A bond where electrons are shared unequally between two atoms, leading to a partial charge.</p> Signup and view all the answers

    Flashcards

    Bond strength and length

    The strength of a covalent bond is directly proportional to the number of electron pairs shared between two atoms. More shared electrons result in a stronger pull between the atoms, causing the bond to be shorter.

    Dative bond

    A covalent bond where both electrons in the shared pair are contributed by one atom. This results in a positive charge on one atom and negative on the other.

    Naming covalent molecules

    The naming of molecules uses a prefix system to indicate the number of atoms present within each molecule.

    Bond polarity

    The difference in electronegativity between two bonded atoms determines the polarity of the bond.

    Signup and view all the flashcards

    Ionic/covalent bond spectrum

    A scale that ranges from ionic to covalent bonding. Although ionic and covalent bonds are considered distinct, they are actually extremes on a spectrum.

    Signup and view all the flashcards

    Covalent bond

    A type of chemical bond where two non-metal atoms share electrons to achieve a stable outer shell configuration.

    Signup and view all the flashcards

    Valence shell

    The outermost shell of an atom, which contains the electrons involved in chemical bonding.

    Signup and view all the flashcards

    Lewis symbols

    Symbols that represent atoms and only show their valence electrons.

    Signup and view all the flashcards

    Octet rule

    The rule that most atoms strive to have eight electrons in their valence shell to achieve stability.

    Signup and view all the flashcards

    Bonding force

    The force of attraction between the nuclei of two atoms and the shared electrons in a covalent bond.

    Signup and view all the flashcards

    Bond length

    The distance between the nuclei of two atoms in a covalent bond, representing the optimal balance of attractive and repulsive forces.

    Signup and view all the flashcards

    Bond energy

    The energy released during the formation of a covalent bond, indicating its stability.

    Signup and view all the flashcards

    Lewis structure

    The process of showing the arrangement of electrons in a molecule, using dots or lines to represent electron pairs.

    Signup and view all the flashcards

    Covalent Bonding

    A covalent bond is formed when two atoms share one or more electrons. This sharing occurs between atoms with similar electronegativity values and results in an electrostatic attraction between the positively charged nuclei and the negatively charged shared electrons.

    Signup and view all the flashcards

    Dative (Co-ordinate) Covalent Bond

    A dative or co-ordinate covalent bond forms when one atom provides both electrons for a shared pair. This occurs when one atom has a lone pair of electrons and the other atom has an empty orbital.

    Signup and view all the flashcards

    Electronegativity

    Electronegativity is the measure of an atom's ability to attract electrons in a chemical bond. It is a relative value, with higher electronegativity indicating a stronger pull towards electrons.

    Signup and view all the flashcards

    Non-Polar Covalent Bond

    When the electronegativity difference between two atoms in a bond is small or zero, the bond is considered non-polar. The electrons are shared equally between the atoms.

    Signup and view all the flashcards

    Polar Covalent Bond

    A polar covalent bond occurs when the electronegativity difference between two atoms is significant, resulting in an uneven sharing of electrons. This creates a partial positive charge (δ+) on the less electronegative atom and a partial negative charge (δ-) on the more electronegative atom.

    Signup and view all the flashcards

    VSEPR Theory

    The VSEPR (Valence Shell Electron Pair Repulsion) theory predicts the shape of molecules based on the repulsion between electron pairs in the valence shell of the central atom. This repulsion causes electron pairs to arrange themselves as far apart as possible, minimizing their interactions.

    Signup and view all the flashcards

    Valence Bond Theory

    Valence bond theory describes covalent bonding in terms of the overlap of atomic orbitals. When two atomic orbitals overlap, they form a new molecular orbital that can hold two electrons. This overlap can be head-to-head (sigma bond) or side-to-side (pi bond).

    Signup and view all the flashcards

    Delocalized Electrons

    Electrons that aren't tied to a specific atom or bond in a molecule, ion, or metal. They move freely within the structure.

    Signup and view all the flashcards

    Resonance Structures

    Different Lewis structures that can be drawn for the same molecule or ion, each showing a different distribution of electrons.

    Signup and view all the flashcards

    Resonance Hybrid

    The true structure of a molecule or ion, an average of all its possible resonance structures. It shows delocalized electrons and bond lengths that are intermediate between single and double bonds.

    Signup and view all the flashcards

    Most Likely Resonance Structure

    The structure of a molecule or ion that minimizes formal charges and places negative charges on the most electronegative atoms.

    Signup and view all the flashcards

    Incomplete Octet

    When a molecule's central atom has less than 8 electrons in its valence shell.

    Signup and view all the flashcards

    Expanded Octet

    When a molecule's central atom has more than 8 electrons in its valence shell.

    Signup and view all the flashcards

    Odd Number of Valence Electrons

    When a molecule has an odd number of valence electrons, making it impossible for all atoms to have a full octet.

    Signup and view all the flashcards

    Electron Domains

    The total number of electron groups (bonds and lone pairs) surrounding the central atom in a molecule or ion.

    Signup and view all the flashcards

    Electron Domain Geometry

    The arrangement of electron domains around the central atom, regardless of the type of bond.

    Signup and view all the flashcards

    Molecular Shape

    The actual shape of a molecule or ion, taking into account the repulsions between bonding pairs and lone pairs.

    Signup and view all the flashcards

    Linear Geometry

    Two electron groups around the central atom result in a linear arrangement.

    Signup and view all the flashcards

    Trigonal Planar Geometry

    Three electron groups around the central atom result in a flat, triangular arrangement.

    Signup and view all the flashcards

    Tetrahedral Geometry

    Four electron groups around the central atom result in a pyramid-like arrangement.

    Signup and view all the flashcards

    Trigonal Bipyramidal Geometry

    Five electron groups around the central atom result in a shape with two pyramids connected at their bases.

    Signup and view all the flashcards

    Octahedral Geometry

    Six electron groups around the central atom result in a symmetrical, cube-like arrangement.

    Signup and view all the flashcards

    Lone Pair Repulsion

    Lone pairs exert greater repulsion than bonding pairs, causing a distortion in the molecular shape.

    Signup and view all the flashcards

    Molecular Shape Determination

    The shape of a molecule depends on the number of lone pairs and bonding pairs around the central atom.

    Signup and view all the flashcards

    What are the limitations of VSEPR theory and what does Valence bond theory offer?

    The Valence Shell Electron Pair Repulsion (VSEPR) theory provides the shape of molecules and ions, but offers no information regarding the orbitals within the molecule or the characteristics of covalent bonds. The Valence Bond theory focuses on answering these specific questions.

    Signup and view all the flashcards

    What is the key characteristic of a sigma bond?

    Sigma bonds are characterized by symmetrical electron density along the axis connecting the nuclei of the bonded atoms, resulting in a strong electrostatic attraction that holds the atoms together.

    Signup and view all the flashcards

    What defines a pi bond?

    A pi bond is a type of covalent bond where the electron density lies above and below the plane of the bonded atoms. Unlike sigma bonds, electrons are delocalized in a pi bond, leading to weaker electrostatic attraction between the electrons and the nuclei. This also makes pi bonds more susceptible to breaking.

    Signup and view all the flashcards

    What is molecular geometry?

    The spatial arrangement of the lone pairs and bonded atoms surrounding a central atom is called the molecular geometry.

    Signup and view all the flashcards

    What is a hybrid orbital?

    Hybrid orbitals are formed by mixing the atomic orbitals of the same atom.

    Signup and view all the flashcards

    What are the characteristics of sp3 hybridization?

    Sp3 hybridization involves the mixing of one s and three p orbitals to produce four equivalent sp3 hybrid orbitals. This hybridization occurs for central atoms that have four electron domains (four bonds or two bonds and two lone pairs). sp3 hybrid orbitals have a tetrahedral shape, resulting in a tetrahedral geometry of the molecule. The presence of lone pairs can alter the shape of the molecule from true tetrahedral geometry to trigonal pyramidal or bent.

    Signup and view all the flashcards

    What is hybrid orbital theory?

    Hybrid orbitals are formed by mixing the atomic orbitals of the same atom.

    Signup and view all the flashcards

    How does the geometry of sp3 hybridization influence the shape of molecules?

    The geometry of sp3 hybridization is tetrahedral. This means that the four hybrid orbitals point towards the corners of a tetrahedron, resulting in a tetrahedral molecular geometry when the central atom only forms bonds. However, the presence of lone pairs on the central atom can distort the shape of the molecule.

    For instance, if the central atom has three bonds and one lone pair, the molecular geometry will be trigonal pyramidal. If the central atom has two bonds and two lone pairs, the molecular geometry will be bent. This distortion happens because the lone pairs exert more repulsion than bonding pairs, pushing the bonded atoms closer to each other.

    Signup and view all the flashcards

    Study Notes

    Covalent Bonding

    • Covalent bonding occurs when atoms share electrons to achieve a stable electron configuration
    • Atoms gain stability by sharing electrons, rather than losing or gaining them (as in ionic bonding).
    • Covalent bonds are classified as single, double, or triple, depending on the number of shared electron pairs (2, 4, or 6 respectively).
    • Bond strength and length are related to the number of shared electrons; more shared electrons increase bond strength but decrease the bond length.

    Dative/Coordinate Covalent Bonds

    • A dative bond is a type of covalent bond in which both electrons in the shared pair come from the same atom.
    • Illustrated with examples like H₃O⁺ and NH₄⁺.

    Bond Polarity and Electronegativity

    • Electronegativity is the measure of an atom's ability to attract bonding electrons.
    • Differences in electronegativity between atoms in a bond determine the polarity of the bond (nonpolar, polar, ionic). A greater difference results in a greater ionic character and a less electronegative atom will have a partial positive charge.
    • Differences in electronegativity are often displayed using the Pauling scale.

    Lewis Structures

    • Lewis structures show the arrangement of atoms and valence electrons in a molecule or polyatomic ion.
    • They illustrate covalent bonds as lines between atoms, and lone/non-bonding pairs as dots.
    • Resonance structures, show resonance is a way of describing molecules which have more than one possible Lewis structure; the true structure is an intermediate form, known as a resonance hybrid.

    Bond Length and Bond Strength

    • Bond length is the distance between the nuclei of two bonded atoms.
    • Bond strength (or bond enthalpy) is the energy required to break the bond.
    • Bond length and strength are related; longer bonds have lower strength.

    Molecular Shapes (VSEPR Theory)

    • Valence Shell Electron Pair Repulsion (VSEPR) theory predicts molecular shapes by considering the repulsion between electron pairs around a central atom.
    • Electron domains (both bonding and lone pairs) arrange themselves to maximize separation.
    • Common shapes include linear, trigonal planar, tetrahedral, trigonal bipyramidal, and octahedral.

    Molecular Polarity

    • Polar molecules have a dipole moment, which is a measure of the polarity of the molecule.
    • If the individual bond dipoles in a molecule cancel out, the molecule is nonpolar, if they don't, it will be polar.
    • A molecule's polarity depends on both its bond polarity and its molecular geometry.

    Resonance Structures

    • Resonance structures are used when a single Lewis structure cannot adequately represent the bonding in a molecule.
    • Multiple Lewis structures are drawn in these cases by shifting the locations of electrons and identifying resonance hybrids as the actual structure.
    • The actual structure is a resonance hybrid, an intermediate form between all resonance formulas.

    Exceptions to the Octet Rule

    • The octet rule (8 valence electrons) is not always followed; some elements can have more or less than 8 valence electrons around the central atom in their structures.
    • Incomplete octets are found in molecules with less than 8 electrons around the central atom.
    • Expanded octets are found in molecules with more than 8 electrons around the central atom.
    • Examples of elements/atoms that can show these exceptions: boron, phosphorus, and sulfur.

    Valence Bond Theory

    • Valence bond theory describes covalent bonding in terms of overlapping atomic orbitals forming molecular orbitals.
    • Two types of bonds are important in the theory: sigma (σ) and pi (π) bonds.
    • Sigma bonds result from end-to-end, or axial overlap of atomic orbitals.
    • Pi bonds result from sideways, or lateral, overlap.
    • Hybridization (mixing atomic orbitals to form new hybrid orbitals) explains more complex bonding scenarios, like double or triple bonds.

    Hybrid Orbitals

    • Hybrid orbitals are combinations of atomic orbitals that result when atoms form covalent bonds.
    • Common types include sp, sp², and sp³.
    • The number of hybrid orbitals formed corresponds to the number of atomic orbitals involved in the mixing/hybridization process: for example sp³ are formed when one 2s and three 2p orbitals mix to four equivalent sp³ orbitals. Each hybrid orbital contains one electron. These orbitals align in space to maximize the distances between each other, forming different geometries.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Description

    Explore the fundamental principles of covalent bonding, including the behavior of non-metal atoms, the octet rule, and Lewis structures. This quiz covers the stability of atoms, bonding characteristics, and the representation of electrons in chemical formulas. Test your understanding of these essential chemistry concepts!

    More Like This

    The Octet Rule Quiz
    5 questions

    The Octet Rule Quiz

    GentleHawkSEye4428 avatar
    GentleHawkSEye4428
    Octet Rule and Covalent Bonding
    15 questions
    Use Quizgecko on...
    Browser
    Browser