BSCH101 Chemistry Practice Test Set 1

Bond Energy and Reactivity

• Decreasing order of bond energy: O2 > O2- > O22-
• O2 exhibits strong double bonds, contributing to higher reactivity, while O22- has increased electron repulsion, decreasing stability.

Existence of He2

• Helium (He2) does not exist due to its closed-shell electron configuration, resulting in no available bonding orbitals to form stable diatomic molecules.

Energy Absorption in Quantum Jumps

• Energy absorbed during an electron's transition from the second to third quantum level calculated using the Rydberg formula or transitions in hydrogen-like atoms.
• Use the formula: ΔE = -13.6 eV (Z^2) (1/n1^2 - 1/n2^2) if Z=1.

Band Theory and Molecular Orbital Theory

• Band theory explains electrical conductivity in solids, emphasizing the overlap of atomic orbitals forming continuous energy bands.
• Pi molecular orbital theory for 1,3-butadiene: involves the delocalization of pi electrons across multiple p-orbitals, resulting in resonance stability.

Ligands and CFSE Calculation

• Ligands are ions or molecules that donate pairs of electrons to a central metal atom in a coordination complex.
• Crystal Field Stabilization Energy (CFSE) for [CrCl6]3- involves the calculation based on the electron configuration and the ligand field, resulting in a CFSE value influenced by the geometry and splitting of d-orbitals.

Color of Cu(H2O)6^2+ vs. Zn(H2O)6^2+

• [Cu(H2O)6]2+ appears blue due to the presence of unpaired d-electrons, allowing for d-d transitions that absorb specific wavelengths of light.
• [Zn(H2O)6]2+ is colorless, as its d-orbitals are fully filled, resulting in no electron transitions in the visible spectrum.

Color of Ti(H2O)6^3+

• [Ti(H2O)6]3+ is often colored due to having partially filled d-orbitals that allow for electronic transitions, exhibiting various shades depending on ligand influence.

Cu2+ and Square Planar Preference

• Cu2+ prefers square planar geometry over tetrahedral because of reduced electron repulsion in the d9 configuration and stabilization from ligand interactions in a planar arrangement.

Spectrochemical Series

• The spectrochemical series orders ligands based on their ability to split d-orbitals, influencing the color and magnetic properties of the resulting complexes.
• Strong field ligands, like CN-, cause greater splitting and often lead to low spin configurations, compared to weak field ligands like I-.

Tetrahedral Complexes and Spin States

• Tetrahedral complexes tend to be high spin due to smaller crystal field splitting energy (Δ), allowing for more unpaired electrons.
• Electron pairing in d-orbitals is less favored in tetrahedral geometries compared to octahedral complexes, which increases magnetic properties.

Test your knowledge of key chemistry concepts with this BSCH101 practice test. The quiz covers topics such as bond energy, molecular theories, and electron transitions. Perfect for preparing for your full marks evaluation!