Chem Topics Study Guide for Bio II Honors/Chem II Honors Placement Exam

Chemistry 1 Final Assessment Topics

Remember to bring your molecular model kit to the final assessment.

Molecular Structure and Geometry

• Lewis Structures

  • Ability to draw Lewis Structures for molecules by determining the total number of valence electrons and arranging them to satisfy the octet rule.

• Formal Charge Calculation

  • Calculate the formal charge of any atom in the molecule using the formula: Formal Charge = (Valence Electrons) - (Non-Bonding Electrons) - 0.5*(Bonding Electrons).

• Hybridization Identification

  • To find hybridization, determine the steric number by adding the number of bonded atoms and lone pairs around the atom. Use the steric number to identify hybridization:

    • 2 = sp

    • 3 = sp2

    • 4 = sp3

    • 5 = sp3d

    • 6 = sp3d2

• Molecular Geometry

  • Determine the molecular geometry by using VSEPR theory. Draw the Lewis structure, count the electron pairs, and use the shapes corresponding to the number of electron pairs (e.g., tetrahedral, trigonal planar).

• Bond Angles

  • State bond angles based on the molecular geometry determined from VSEPR theory (e.g., 180°, 120°, 109.5°).

• Polarity

  • Determine polarity by analyzing the electronegativity differences between atoms and checking for symmetry in the molecule. If the difference is >0.4, the bond is polar; analyze the geometry to assess overall molecular polarity (net dipole moment).

• Resonance Structures

  • Assess and draw resonance structures by moving electrons in different Lewis structures while keeping the overall charge constant and obeying the octet rule.

• Bond-Line Notation Conversion

  • Convert between Bond-Line Notation and Lewis Structures by translating between the shorthand form and expanded structural formulas, while checking atom connectivity to derive the molecular formula.

• Model Building

  • Build a model of a specified molecule using the molecular model kit by assembling atoms into the correct spatial arrangement and bonding them appropriately.

Periodic Trends

• Trends in the Periodic Table

  • Explain periodic trends with respect to nuclear charge and shielding effects by analyzing trends in atomic radius, ionization energy, and electronegativity across and down the periodic table.

• Electron Configuration

  • Writing Configurations

    • Write the electron configuration for an atom or ion by starting with the lowest energy orbitals and filling them according to the Aufbau principle.

  • Orbital (Energy) Diagrams

    • Draw the orbital (energy) diagram for the atom or ion by filling orbitals in the order of increasing energy levels while following the Pauli Exclusion Principle and Hund's Rule.

  • Orbital Diagram Rules

    • Aufbau Principle: Fill from low to high energy.

    • Hund's Rule: Fill each orbital with one electron before pairing.

    • Pauli Exclusion Principle: No two electrons can have the same spin in one orbital.

Intermolecular Forces

• Forces Between Molecules

  • Explain different types and relative strengths of intermolecular forces by comparing hydrogen bonds, dipole-dipole interactions, and London dispersion forces based on molecular structure and polarity.

• Molecular Polarity

  • Identify polar vs. nonpolar molecules by examining electronegativity differences and symmetry (e.g., linear molecules can be nonpolar while angular structures with polar bonds can be polar).

• Molecular Interactions

  • Explain how molecules interact with one another and with water by considering hydrogen bonding, ionic interactions, and solubility factors based on molecular characteristics.