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Questions and Answers
What type of bond is primarily formed through the transfer of electrons between atoms?
What type of bond is primarily formed through the transfer of electrons between atoms?
The octet rule states that atoms are stable when surrounded by six electrons.
The octet rule states that atoms are stable when surrounded by six electrons.
False
What are valence electrons?
What are valence electrons?
Electrons found in the outermost shell of an atom that are involved in bonding.
In a Lewis symbol, unpaired dots represent the number of _______ available for bonding.
In a Lewis symbol, unpaired dots represent the number of _______ available for bonding.
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Which electron configuration represents a stable Chlorine ion (Cl–)?
Which electron configuration represents a stable Chlorine ion (Cl–)?
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Match the following bonding types with their characteristics:
Match the following bonding types with their characteristics:
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All transition metals can achieve a noble gas electron configuration.
All transition metals can achieve a noble gas electron configuration.
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Atoms tend to gain, lose, or share electrons until they achieve a full _______ configuration.
Atoms tend to gain, lose, or share electrons until they achieve a full _______ configuration.
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What type of hybridization occurs in the BeF2 molecule?
What type of hybridization occurs in the BeF2 molecule?
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All molecules with a tetrahedral electron pair geometry are sp hybridized.
All molecules with a tetrahedral electron pair geometry are sp hybridized.
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How many unhybridized p orbitals remain after sp2 hybridization?
How many unhybridized p orbitals remain after sp2 hybridization?
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The bond angle for a molecule with sp3 hybridization is ______.
The bond angle for a molecule with sp3 hybridization is ______.
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Match the following hybridizations with their corresponding electron-pair geometries:
Match the following hybridizations with their corresponding electron-pair geometries:
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Which hybridization is required for octahedral electron-pair geometries?
Which hybridization is required for octahedral electron-pair geometries?
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What is the significance of hybridization in explaining molecular geometry?
What is the significance of hybridization in explaining molecular geometry?
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For every n atomic orbitals mixed, n hybrid orbitals are produced.
For every n atomic orbitals mixed, n hybrid orbitals are produced.
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Which electrons are lost first when transition metals form ions?
Which electrons are lost first when transition metals form ions?
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All polyatomic ions contain only ionic bonds.
All polyatomic ions contain only ionic bonds.
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What is the term for a chemical bond formed by the sharing of a pair of electrons?
What is the term for a chemical bond formed by the sharing of a pair of electrons?
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The distance between the nuclei of the atoms in a bond is called the __________.
The distance between the nuclei of the atoms in a bond is called the __________.
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Which of the following describes a polar covalent bond?
Which of the following describes a polar covalent bond?
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Electronegativity decreases across a period in the periodic table.
Electronegativity decreases across a period in the periodic table.
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What does a dipole moment quantify in a molecule?
What does a dipole moment quantify in a molecule?
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In Lewis structures, unshared electron pairs are represented as __________.
In Lewis structures, unshared electron pairs are represented as __________.
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Match the following terms with their definitions:
Match the following terms with their definitions:
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What happens to bond distances as the bond type becomes stronger?
What happens to bond distances as the bond type becomes stronger?
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Covalent bonds can only involve two atoms.
Covalent bonds can only involve two atoms.
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What is the lowest value on the Pauling electronegativity scale?
What is the lowest value on the Pauling electronegativity scale?
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The most stable Lewis structure has the __________ formal charge on the most electronegative atom.
The most stable Lewis structure has the __________ formal charge on the most electronegative atom.
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What do resonance structures represent?
What do resonance structures represent?
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Resonance structures indicate that the atoms have real charges associated with them.
Resonance structures indicate that the atoms have real charges associated with them.
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Name one common molecule that exhibits resonance.
Name one common molecule that exhibits resonance.
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A molecule with three bonds and one lone pair has __________ electron domains.
A molecule with three bonds and one lone pair has __________ electron domains.
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Match the exceptions to the octet rule with their descriptions:
Match the exceptions to the octet rule with their descriptions:
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Which statement is true regarding benzene?
Which statement is true regarding benzene?
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Atoms in the second period can have expanded octets.
Atoms in the second period can have expanded octets.
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What is the key factor in determining molecular geometry?
What is the key factor in determining molecular geometry?
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The model used to predict molecular shape based on electron domain repulsion is called __________.
The model used to predict molecular shape based on electron domain repulsion is called __________.
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What type of molecular geometry does a molecule with four electron domains adopt?
What type of molecular geometry does a molecule with four electron domains adopt?
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Lone pairs are considered when describing molecular geometry.
Lone pairs are considered when describing molecular geometry.
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What is the molecular shape of NH3?
What is the molecular shape of NH3?
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Match the electron-domain geometries with the number of electron domains:
Match the electron-domain geometries with the number of electron domains:
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Which molecules typically have an odd number of electrons?
Which molecules typically have an odd number of electrons?
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The bond angles in a tetrahedral molecule are typically __________ degrees.
The bond angles in a tetrahedral molecule are typically __________ degrees.
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What happens to the bond angles as the number of nonbonding electron pairs increases?
What happens to the bond angles as the number of nonbonding electron pairs increases?
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Molecules with polar bonds are always polar themselves.
Molecules with polar bonds are always polar themselves.
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What is the molecular geometry of molecules with four atoms that have a trigonal pyramidal shape?
What is the molecular geometry of molecules with four atoms that have a trigonal pyramidal shape?
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The molecule H2O has a bond angle of _____ degrees.
The molecule H2O has a bond angle of _____ degrees.
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Match the following molecular geometries with their characteristics:
Match the following molecular geometries with their characteristics:
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What is the bond angle in ammonia (NH3)?
What is the bond angle in ammonia (NH3)?
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In CO2, the individual dipoles cancel out, resulting in a nonpolar molecule.
In CO2, the individual dipoles cancel out, resulting in a nonpolar molecule.
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What determines the overall dipole moment in a triatomic molecule?
What determines the overall dipole moment in a triatomic molecule?
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The bond dipole in a covalent bond is due to the separation of _____ and _____ charges.
The bond dipole in a covalent bond is due to the separation of _____ and _____ charges.
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What is the molecular shape when there are five bonding pairs and one lone pair in an octahedral structure?
What is the molecular shape when there are five bonding pairs and one lone pair in an octahedral structure?
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VSEPR theory explains the repulsion between bonded pairs only.
VSEPR theory explains the repulsion between bonded pairs only.
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What is the role of the electron pairs in a trigonal bipyramidal structure?
What is the role of the electron pairs in a trigonal bipyramidal structure?
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In an octahedral geometry, pairs of electrons in the plane are at _____ degrees to each other.
In an octahedral geometry, pairs of electrons in the plane are at _____ degrees to each other.
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Which electron domain geometry has a bond angle of 120 degrees?
Which electron domain geometry has a bond angle of 120 degrees?
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Study Notes
Chemical Bonding Concepts
- Chemical bonds form when atoms or ions are strongly attracted.
- Bond formation involves sharing or transferring electrons between atoms.
- Bond types include ionic (electrostatic forces between ions, e.g., NaCl), covalent (electron sharing, e.g., Cl₂), and metallic (metal nuclei in a "sea" of electrons, e.g., Na).
Lewis Symbols
- Valence electrons participate in bonding.
- Valence electrons reside in the outermost shell.
- Lewis symbols (or electron-dot symbols) pictorially represent valence electrons as dots around the element symbol.
- Unshared electrons are shown as dots, and bonding pairs as a line.
- Dots are typically arranged around the element symbol.
Octet Rule
- Atoms gain, lose, or share electrons to obtain eight valence electrons.
- This octet fulfills s²p⁶ (noble gas configuration).
- Stability is assumed when an atom has eight electrons.
Electron Configuration of Ions
- Stable ions form by adding or removing electrons to achieve a noble gas configuration(s²p⁶).
- Example: Na⁺ (loses 1 electron from 3s to form [Ne] )
- Example: Cl⁻ (gains 1 electron to form [Ar])
Transition Metal Ions
- Transition metals often have 1+, 2+, or 3+ charges.
- Transition metals do not necessarily achieve a noble-gas configuration.
- Electrons are removed from the 4s subshell before 3d, etc., to reach the desired charge.
Polyatomic Ions
- Polyatomic ions are charged groups of covalently bonded atoms.
- Examples include NH₄⁺ and CO₃²⁻.
- These ions are stable units carrying a charge.
Covalent Bonding
- Many substances do not exhibit ionic properties.
- Covalent bonding involves electron pairs shared by atoms.
- Each atom achieves a noble gas configuration.
Lewis Structures
- Lewis structures represent covalent bonds using lines and dots to show shared and unshared (lone) pairs of electrons.
- Shared pairs are represented by lines connecting atoms (bonds).
- Unshared pairs are represented by dots.
Multiple Bonds
- Two or more electron pairs can be shared between atoms (multiple bonds).
- A single bond shares one pair.
- A double bond shares two pairs.
- A triple bond shares three pairs.
- Bond lengths decrease with increasing bond order (single < double < triple).
Bond Polarity and Electronegativity
- Bond polarity reflects uneven electron sharing in a covalent bond.
- Nonpolar covalent bonds: Equal electron sharing.
- Polar covalent bonds: Uneven electron sharing due to electronegativity difference. Electronegativity: The tendency of an atom in a molecule to attract electrons.
- Pauling electronegativity scale (0.7-4.0), increasing from left to right across a period.
Dipole Moments
- Polar molecules have separated positive and negative charges.
- Dipole moment quantifies the magnitude and direction of the charge separation in a molecule.
- The dipole moment (μ) = Qr (product of charge and distance). -Measured in debyes (D).
- Arrow in the Lewis structure indicates polarity. The arrow points toward the more negative end.
Drawing Lewis Structures Procedure
- Determine total valence electrons, adding for anions and subtracting for cations.
- Identify the central atom.
- Surround the central atom with the other atoms.
- Add single bonds between the atoms.
- Complete octets for outer atoms.
- Complete the octet for the central atom; use multiple bonds if necessary.
Formal Charge
- Formal charge is a theoretical charge of an atom in a molecule assuming equal sharing.
- Used to determine the most stable Lewis structure.
- Most stable structure minimizes formal charge on atoms and places the negative charge on more electronegative atoms.
Resonance Structures
- Some molecules cannot be represented adequately by a single Lewis structure.
- They are represented by resonance structures which are Lewis structures that differ only in the placement of electrons.
- The true structure is a "hybrid" of resonance structures (represented by double-headed arrows).
- Examples include O₃, NO₃⁻, SO₃.
Benzene
- Benzene (C₆H₆) is a cyclic, planar hydrocarbon with alternating single and double bonds.
- The actual bond lengths are equal.
- Represented by a hexagon with a circle inside to indicate the delocalized electrons.
Exceptions to the Octet Rule
- Odd number of electrons. Examples: NO, NO₂
- Less than an octet. Example: BF₃
- Expanded octet. Example: PCl₅
Molecular Geometry and Bonding Theory
- VSEPR model: Valence Shell Electron Pair Repulsion (electron domains arrange to minimize repulsion).
- Electron pair geometry versus molecular geometry
- Hybridization of atomic orbitals to achieve best match to VSEPR arrangement.
- Hybrid orbitals form by combining atomic orbitals, matching the electron domain geometry.
- sp, sp² and sp³ hybridizations, and mixing with d orbitals for expanded octets (sp³d and sp³d²)
Molecular Shape and Polarity
- Molecular geometry affects polarity and dipole moments.
- Polar molecules have an uneven distribution of charge.
- Use bond dipoles and their vector sum to determine molecular polarity.
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Description
This quiz covers the fundamentals of chemical bonding, including types of bonds, electron-sharing mechanisms, and the principles behind Lewis symbols. It also explores the Octet Rule and its significance in achieving stable electron configurations in atoms. Test your understanding of these core concepts in chemistry!
