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Questions and Answers
What is a chemical bond?
What is a chemical bond?
A force that holds two or more atoms together.
What does the octet rule state?
What does the octet rule state?
During the formation of a chemical compound, each atom has eight electrons in its highest occupied energy level by gaining, losing, or sharing electrons.
The ions of some transition elements have the usual noble gas valence shell of ns2np6.
The ions of some transition elements have the usual noble gas valence shell of ns2np6.
False (B)
What is the rule of two an exception to?
What is the rule of two an exception to?
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What are the forces that hold atoms together within a molecule called?
What are the forces that hold atoms together within a molecule called?
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Ionic bonding is formed by electron sharing between two non-metals.
Ionic bonding is formed by electron sharing between two non-metals.
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What type of chemical bond is formed when a metal cation bonds with a non-metal anion?
What type of chemical bond is formed when a metal cation bonds with a non-metal anion?
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What type of chemical bond refers to the interaction between delocalized electrons and metal nuclei?
What type of chemical bond refers to the interaction between delocalized electrons and metal nuclei?
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What does a Lewis electron-dot symbol represent?
What does a Lewis electron-dot symbol represent?
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What is the optimum distance between nuclei in a covalent bond called?
What is the optimum distance between nuclei in a covalent bond called?
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What is a Lewis structure?
What is a Lewis structure?
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Which of the following are steps to draw a Lewis structure? (Select all that apply)
Which of the following are steps to draw a Lewis structure? (Select all that apply)
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What type of bond is formed when both electrons are donated by one of the atoms?
What type of bond is formed when both electrons are donated by one of the atoms?
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What is a resonance structure?
What is a resonance structure?
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Atoms NEVER move; only electrons move.
Atoms NEVER move; only electrons move.
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What are the three groups of exceptions to the octet rule in covalent bonding? (Select all that apply)
What are the three groups of exceptions to the octet rule in covalent bonding? (Select all that apply)
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The main difference between polar and nonpolar covalent bonds is that polar covalent bonds have electrons unequally shared, while nonpolar covalent bonds have electrons equally shared.
The main difference between polar and nonpolar covalent bonds is that polar covalent bonds have electrons unequally shared, while nonpolar covalent bonds have electrons equally shared.
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Polar covalent bonds are soluble in water.
Polar covalent bonds are soluble in water.
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What is a dipole moment?
What is a dipole moment?
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A molecule that carries opposite charges is called a dipole.
A molecule that carries opposite charges is called a dipole.
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The net dipole moment of a molecule arises as the sum of the individual bond dipoles.
The net dipole moment of a molecule arises as the sum of the individual bond dipoles.
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What is the SI unit of dipole moment?
What is the SI unit of dipole moment?
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Covalent compounds have low melting points.
Covalent compounds have low melting points.
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Covalent compounds are generally insoluble in water.
Covalent compounds are generally insoluble in water.
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Non-polar covalent compounds are non-electrolytes.
Non-polar covalent compounds are non-electrolytes.
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What determines the molecular geometry of a molecule?
What determines the molecular geometry of a molecule?
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What are the five molecular geometries? (Select all that apply)
What are the five molecular geometries? (Select all that apply)
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What does the notation ABxEy represent?
What does the notation ABxEy represent?
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What is electron pair geometry?
What is electron pair geometry?
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One set of electron may be one single bond, one double bond, one triple bond, one lone pair, or one electron.
One set of electron may be one single bond, one double bond, one triple bond, one lone pair, or one electron.
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Linear electron pair arrangement has two sets of electrons around the central atom.
Linear electron pair arrangement has two sets of electrons around the central atom.
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The strength of the metallic bond depends on the number of electrons in the delocalized sea of elections and the arrangement of the atoms.
The strength of the metallic bond depends on the number of electrons in the delocalized sea of elections and the arrangement of the atoms.
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The electron-sea model proposes that all the metal atoms in a metallic solid contribute their valence electrons to form a sea of electrons, which are held by any specific atom and can't easily move.
The electron-sea model proposes that all the metal atoms in a metallic solid contribute their valence electrons to form a sea of electrons, which are held by any specific atom and can't easily move.
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Metallic bonds show typical metallic properties such as high electrical conductivity, lustre, and high heat conductivity.
Metallic bonds show typical metallic properties such as high electrical conductivity, lustre, and high heat conductivity.
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Most metals are liquids with low melting points but higher boiling points.
Most metals are liquids with low melting points but higher boiling points.
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The basic principle of the valence bond theory is that a covalent bond forms when orbitals of two atoms overlap and the overlap region is occupied by a pair of electrons.
The basic principle of the valence bond theory is that a covalent bond forms when orbitals of two atoms overlap and the overlap region is occupied by a pair of electrons.
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The strength of a bond between two atoms always depends on the extent of the overlap between two orbitals.
The strength of a bond between two atoms always depends on the extent of the overlap between two orbitals.
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Hybridization is the blending of s, p, and d orbitals to explain bond formation.
Hybridization is the blending of s, p, and d orbitals to explain bond formation.
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The number of hybrid orbitals formed always equals the number of atomic orbitals that mix.
The number of hybrid orbitals formed always equals the number of atomic orbitals that mix.
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Hybridization occurs only during bond formation and not in a single gaseous atom.
Hybridization occurs only during bond formation and not in a single gaseous atom.
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Sp hybridization occurs when one s and one p orbital in an atom's shell combine to form two new equivalent orbitals.
Sp hybridization occurs when one s and one p orbital in an atom's shell combine to form two new equivalent orbitals.
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Sp2 hybridization has a central atom that produces two equivalent orbitals.
Sp2 hybridization has a central atom that produces two equivalent orbitals.
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Sp3 hybridization results in four equivalent orbitals.
Sp3 hybridization results in four equivalent orbitals.
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Sp3d2 hybridization forms seven identical orbitals.
Sp3d2 hybridization forms seven identical orbitals.
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Sp3d3 hybridization results in seven identical orbitals.
Sp3d3 hybridization results in seven identical orbitals.
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The linear sp2 hybridization occurs when two electron groups are involved with an orbital angle of 180°.
The linear sp2 hybridization occurs when two electron groups are involved with an orbital angle of 180°.
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The trigonal planar hybridization occurs when three atoms are involved with an orbital angle of 120 degrees.
The trigonal planar hybridization occurs when three atoms are involved with an orbital angle of 120 degrees.
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The tetrahedral hybridization occurs when five election groups are involved, resulting in sp3 hybridization with an angle of 109.5°.
The tetrahedral hybridization occurs when five election groups are involved, resulting in sp3 hybridization with an angle of 109.5°.
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Trigonal bipyramidal sp3d hybridization occurs when four electron groups are involved with an orbital angle of 90° and 120 degrees.
Trigonal bipyramidal sp3d hybridization occurs when four electron groups are involved with an orbital angle of 90° and 120 degrees.
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The octahedral sp3d2 hybridization occurs when six electron groups are involved with an orbital angle of 90 degrees.
The octahedral sp3d2 hybridization occurs when six electron groups are involved with an orbital angle of 90 degrees.
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Molecular orbital theory is based on the fact that electrons are not the substantive little dots as in Lewis structures.
Molecular orbital theory is based on the fact that electrons are not the substantive little dots as in Lewis structures.
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Study Notes
Chemical Bonding and Structure
- Chemical bond: A force holding two or more atoms together, creating molecules and crystals.
- Octet rule: During compound formation, atoms gain, lose, or share electrons to achieve a full outer electron shell (eight electrons). This allows atoms to become isoelectronic with noble gases.
- Intramolecular forces: Forces holding atoms together within a molecule.
- Intermolecular forces: Forces between molecules.
- Limitation of octet rule: Some transition and post-transition elements do not follow the octet rule.
Types of Chemical Bonding
- Ionic bonding: Electron transfer from a metal to a non-metal, forming ions. Ionic compounds are formed when metal cations bond with non-metal anions (exception: ammonium ion).
- Covalent bonding: Sharing of electrons between non-metals. Non-polar covalent bonding occurs when electronegativity values are similar, while polar covalent bonding results from significant electronegativity differences.
- Metallic bonding: Delocalized electrons shared among a lattice of positively charged metal ions.
Formation of Ionic Bonding
- Formation of ions involves more than just energy levels but depends on the overall stability compared to elemental forms.
- Lattice energy is a measure of the energy released when ions combine to form a solid ionic compound. It strongly influences melting point, hardness, and solubility of the compound
- Factors affecting ionic bonding include ionization energy and electron affinity.
Lattice Energy
- Lattice energy: Energy required to break one mole of ionic solid into gaseous ions.
- Factors that affect lattice energy include: ion size and magnitude of charge.
- Usually measured in kilojoules per mole (kJ/mol).
- Lattice energy is crucial to predicting properties of ionic compounds.
Factors Affecting Formation of Ionic Bonding
- lonization energy: Elements with lower ionization energy are more likely to form cations.
- Electron affinity: Elements with higher electron affinity are more likely to form anions.
- Lattice energy: Larger lattice energies favor the formation of ionic compounds.
- Exceptions to the octet rule exist in ionic compounds (e.g., less than an octet or more than an octet).
Properties of Ionic Compounds
- Typically crystalline solids with high melting and boiling points.
- Generally soluble in water but insoluble in non-polar solvents,
- Often conduct electricity when molten or dissolved.
Covalent Bonds and Molecular Geometry
- Covalent bonds involve electron sharing.
- Bond length: The optimum distance between atomic nuclei.
- Lone pair: A pair of electrons that are not involved in bonding.
- Molecular geometry is the spatial arrangement of atoms in a molecule.
Lewis Structures
- Simplifies the representation of valence electrons in molecules.
- Electrons are represented as dots or lines.
Single, Double, and Triple Bonds
- Single bonds: Share one pair of valence electrons.
- Double bonds: Share two pairs of valence electrons.
- Triple bonds: Share three pairs of valence electrons.
- Bond length and strength vary with the number of shared electron pairs, with triple bonds being the strongest and shortest.
Coordinate Covalent Bonds
- Bonds in which both electrons are donated from the same atom.
Resonance Structures
- Multiple Lewis structures that contribute to the true electronic structure of a molecule.
- Resonance structures have identical connectivity but different arrangements of electrons.
Exceptions to the Octet Rule in Covalent Bonding
- Less than octet
- More than octet
- Odd number of electrons
Polar and Non-Polar Covalent Molecules
- Polar covalent bonds: Unequal sharing of electrons due to electronegativity differences.
- Non-polar covalent bonds: Equal sharing of electrons due to similar electronegativities
Dipole Moment
- Dipole moment: A measure of the polarity of a molecule.
- Occurs when there's a separation of positive and negative charges or dipoles within the molecule, often in polar covalent bonds
- Dipole moment is measured in debyes (D).
Intermolecular Forces
- Intermolecular forces are forces between molecules
- dipole-dipole forces act between molecules possessing permanent dipoles
- London dispersion forces – atoms form temporary dipoles, temporary dipoles are attractive forces
- Hydrogen bonds are strong dipole-dipole forces involving a hydrogen atom covalently bonded to highly electronegative atoms (especially Nitrogen, oxygen, or fluorine)
Metallic Bonding
- Sharing of delocalized electrons among a lattice of positively charged metal ions.
- Strength depends on the number of valence electrons and the packing of metal atoms.
Chemical Bonding Theories
- Valence bond theory explains covalent bonding through orbital overlap.
- Both Valence shell electron pair repulsion (VSEPR) theory and hybridization are used to predict the shape.
- Molecular orbital theory uses mathematical methods that considers the whole molecule to describe bonding; electron distributions are called molecular orbitals.
Molecular Shape and Molecular Polarity
- Bond polarity and dipole moment
- Overall polarity depends on both bond polarity and molecular shape.
Properties of Covalent Compounds
- Low melting and boiling points due to weak intermolecular forces.
- Poor conductors of heat and electricity due to the lack of free electrons.
Molecular Geometry
- Describes the spatial arrangement of atoms in a molecule.
- Common shapes include linear, trigonal planar, tetrahedral, trigonal pyramidal, and octahedral
- The Valence Shell Electron Pair Repulsion (VSEPR) theory helps predict molecular shapes.
Types of Hybridization
- sp, sp2, sp3, sp3d, sp3d2, sp3d3 (each type uses a mix of s, p, or d orbitals to create new hybrid orbitals, used to predict molecular geometry and shape.
Molecular Orbital Theory (MOT)
- Explains covalent bonding via molecular orbitals.
- Molecular orbitals are formed from combinations of atomic orbitals.
- Bonding and anti-bonding orbitals are distinguished by electron density distribution
Types of Crystals
- Ionic, covalent network, molecular, and metallic,
- These structures affect the properties of solids; bonding type influences the strength, melting point, conductivity, and other physical characteristics of the solid
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Description
Test your knowledge on chemical bonding and molecular structure. This quiz covers concepts such as ionic and covalent bonds, the octet rule, and intermolecular forces. Dive into the intricate details of how atoms interact to form various compounds.
