Bonding and Molecular Structure Flashcards
What are metallic bonds?
Bonds between two metals where electrons are shared in a completely delocalized manner across all atoms in the material.
Define ionic bonds.
Bonds formed between a metal and a non-metal through the transfer of one or more electrons from the metal to the non-metal, creating cations and anions that are held together by Coulombic attractions.
What is a covalent bond?
A type of chemical bond where electrons are shared between two non-metal atoms.
Explain the concept of lattice energy.
The energy released when cations and anions bind to form a crystalline lattice, calculated using Coulomb’s Law.
What does the Born-Oppenheimer approximation assume?
It assumes that the nuclei are fixed and only the electronic wavefunctions need to be considered.
What is the significance of hybridization in bonding?
Hybridization explains how atomic orbitals mix to form new hybrid orbitals that can make covalent bonds, providing insight into molecular geometry and bond properties.
What is the Ketelaar triangle used for?
It is used to plot the average electronegativity against the difference in electronegativity of two atoms to predict the likely bond type.
Define the Aufbau principle as it applies to molecular orbitals.
Electrons fill molecular orbitals starting from the lowest energy level up, following the same rules as atomic orbitals
What are sigma and pi bonds?
Sigma bonds involve head-on overlap of orbitals along the axis connecting two nuclei, while pi bonds involve side-on overlap and are formed in addition to sigma bonds in multiple bonding scenarios.
Explain molecular orbitals.
Molecular orbitals are formed from the linear combination of atomic orbitals (LCAO) and describe the probability distribution of an electron in a molecule.
How does electronegativity difference influence bond type?
Larger differences favor ionic bonds due to electron transfer, smaller differences favor covalent bonds due to electron sharing.
What role does electron configuration play in bonding?
Electron configuration determines how atoms bond, influencing molecular shape and stability through the distribution of electrons in orbitals.
How do ionic bonds form from a quantum mechanical perspective?
Ionic bonds form when there is complete transfer of one or more electrons from one atom to another, creating ions that attract each other.
Describe how covalent bonds form at the quantum level.
Covalent bonds form when atomic orbitals overlap to produce molecular orbitals where electrons are shared between atoms.
How is bond energy related to bond length and bond order?
Generally, higher bond orders result in shorter bond lengths and greater bond energy.
What factors affect lattice energy?
Lattice energy is affected by the charge on the ions and the distance between them; higher charges and shorter distances increase lattice energy.
How does hybridization influence molecular geometry?
Hybridization changes the shapes of atomic orbitals and thus determines the geometry of the molecule, such as linear, trigonal planar, or tetrahedral.
What is the importance of the LCAO method in molecular orbital theory?
LCAO allows for the approximation of molecular orbitals, which are crucial for understanding bonding and antibonding interactions in molecules.
Explain how the concept of bond order can be used to determine the stability of a molecule
Bond order, calculated as the difference between bonding and antibonding electrons divided by two, indicates the stability of a bond; higher bond orders generally mean a more stable bond.
Describe the process of delocalization in metallic bonding.
In metallic bonding, valence electrons are not associated with any particular atom and are free to move throughout the metal, which accounts for properties like electrical conductivity
How do electronegativity differences affect the properties of compounds?
They determine the polarity of bonds and thus influence the physical properties like melting point, boiling point, and solubility.
Discuss the relationship between molecular orbitals and the physical properties of molecules.
The distribution and energy of molecular orbitals determine reactivity, polarity, color, magnetism, and other physical properties.
What is the impact of molecular geometry on reactivity?
Geometry affects how molecules interact with each other, influencing reaction mechanisms, rates, and pathways.
How does bonding affect thermal and electrical conductivity?
Types of bonding influence how easily electrons and heat can move through a substance, with metallic bonds generally facilitating higher conductivity.
Consider the role of molecular symmetry in spectroscopy and reactivity.
Symmetry affects the energy states accessible to a molecule, influencing its spectroscopic signature and how it interacts with other molecules.
What challenges exist in applying MO theory to large molecules?
Computational complexity increases dramatically with the size of the molecule, making it difficult to accurately calculate molecular orbitals and properties.
How do pi bonds affect the stability and reactivity of molecules?
Pi bonds often make molecules less stable but more reactive, particularly in reactions that involve the breaking of these bonds.
Discuss the limitations of using Lewis structures to describe molecular bonding.
Lewis structures do not accurately represent the three-dimensional geometry, nor do they show delocalized electrons or resonance structures effectively.
How do changes in hybridization affect molecular reactivity?
Changes in hybridization can expose or shield certain atoms, affecting how a molecule interacts with reactants.
What are the practical applications of understanding molecular structure and bonding?
It aids in the design of pharmaceuticals, materials science, chemical synthesis strategies, and the prediction of chemical properties and behaviors.
