Chemical Bonding and Structure Quiz
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Questions and Answers

What is a chemical bond?

A force that holds two or more atoms together.

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.

False

What is the rule of two an exception to?

<p>Octet rule</p> Signup and view all the answers

What are the forces that hold atoms together within a molecule called?

<p>Intramolecular forces</p> Signup and view all the answers

Ionic bonding is formed by electron sharing between two non-metals.

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

What type of chemical bond is formed when a metal cation bonds with a non-metal anion?

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

What type of chemical bond refers to the interaction between delocalized electrons and metal nuclei?

<p>Metallic bonding</p> Signup and view all the answers

What does a Lewis electron-dot symbol represent?

<p>An atom or monoatomic ion showing the valence electrons, if present, as dots placed around the letter symbol of the element.</p> Signup and view all the answers

What is the optimum distance between nuclei in a covalent bond called?

<p>Bond length</p> Signup and view all the answers

What is a Lewis structure?

<p>A very simplified representation of the valence shell electrons in a molecule.</p> Signup and view all the answers

Which of the following are steps to draw a Lewis structure? (Select all that apply)

<p>Draw a skeleton structure using single bonds.</p> Signup and view all the answers

What type of bond is formed when both electrons are donated by one of the atoms?

<p>Coordinate covalent bond</p> Signup and view all the answers

What is a resonance structure?

<p>Sets of Lewis structures that describe the delocalization of electrons in a polyatomic ion or a molecule.</p> Signup and view all the answers

Atoms NEVER move; only electrons move.

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

What are the three groups of exceptions to the octet rule in covalent bonding? (Select all that apply)

<p>Molecules containing an even number of electrons</p> Signup and view all the answers

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.

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

Polar covalent bonds are soluble in water.

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

What is a dipole moment?

<p>The product of the magnitude of the charge and the distance between the centers of the positive and negative charges.</p> Signup and view all the answers

A molecule that carries opposite charges is called a dipole.

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

The net dipole moment of a molecule arises as the sum of the individual bond dipoles.

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

What is the SI unit of dipole moment?

<p>Coulomb meter</p> Signup and view all the answers

Covalent compounds have low melting points.

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

Covalent compounds are generally insoluble in water.

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

Non-polar covalent compounds are non-electrolytes.

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

What determines the molecular geometry of a molecule?

<p>The mutual repulsion of valence electrons about an atom in a molecule. The shape is also determined by the central atom and the surrounding atoms and electron pairs.</p> Signup and view all the answers

What are the five molecular geometries? (Select all that apply)

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

What does the notation ABxEy represent?

<p>A molecule with lone pairs.</p> Signup and view all the answers

What is electron pair geometry?

<p>The set of electrons around the central atom.</p> Signup and view all the answers

One set of electron may be one single bond, one double bond, one triple bond, one lone pair, or one electron.

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

Linear electron pair arrangement has two sets of electrons around the central atom.

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

The strength of the metallic bond depends on the number of electrons in the delocalized sea of elections and the arrangement of the atoms.

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

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.

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

Metallic bonds show typical metallic properties such as high electrical conductivity, lustre, and high heat conductivity.

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

Most metals are liquids with low melting points but higher boiling points.

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

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.

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

The strength of a bond between two atoms always depends on the extent of the overlap between two orbitals.

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

Hybridization is the blending of s, p, and d orbitals to explain bond formation.

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

The number of hybrid orbitals formed always equals the number of atomic orbitals that mix.

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

Hybridization occurs only during bond formation and not in a single gaseous atom.

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

Sp hybridization occurs when one s and one p orbital in an atom's shell combine to form two new equivalent orbitals.

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

Sp2 hybridization has a central atom that produces two equivalent orbitals.

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

Sp3 hybridization results in four equivalent orbitals.

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

Sp3d2 hybridization forms seven identical orbitals.

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

Sp3d3 hybridization results in seven identical orbitals.

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

The linear sp2 hybridization occurs when two electron groups are involved with an orbital angle of 180°.

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

The trigonal planar hybridization occurs when three atoms are involved with an orbital angle of 120 degrees.

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

The tetrahedral hybridization occurs when five election groups are involved, resulting in sp3 hybridization with an angle of 109.5°.

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

Trigonal bipyramidal sp3d hybridization occurs when four electron groups are involved with an orbital angle of 90° and 120 degrees.

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

The octahedral sp3d2 hybridization occurs when six electron groups are involved with an orbital angle of 90 degrees.

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

Molecular orbital theory is based on the fact that electrons are not the substantive little dots as in Lewis structures.

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

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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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.

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