Recording-2025-03-13T21:08:08.231Z

Chapter 4 Review

• Ensure understanding by reviewing the quiz from Chapter 4 and focusing on any missed questions.

• Answer key provided for reference but does not explain how to work out problems.

Office Hours & Assistance

• Office hours are changed to Tuesday morning around 9:00-9:30 AM for last-minute questions.

• For specific email queries:

  • Specify the class.

  • Attach screenshots of the problems for context.

Ionic vs. Covalent Compounds

• Important to distinguish between ionic and covalent compounds:

  • Ionic Compounds:

    • Formed between metals and nonmetals, separated by the periodic table's 'ladder'.

    • Involves the transfer of electrons to form ions.

  • Covalent Compounds (Molecular Compounds):

    • Composed of two nonmetals.

    • Involves the sharing of electrons.

• Bonding examples showed lines in drawings representing shared electrons.

• Understand how to determine charges for ionic compounds based on periodic table groups:

  • Group 1: +1 Charge

  • Group 2: +2 Charge

  • Group 3: +3 Charge

  • Group 5: -3 Charge

  • Group 6: -2 Charge

  • Group 7: -1 Charge

• Able to convert between formula and compound name:

  • Use a naming chart for clarity.

  • Metal names stay the same; nonmetals end with 'ide'.

Hydrates and Naming

• Define hydrates as ionic compounds that include water.

• Requires knowledge of prefixes (di-, tri-, tetra-, etc.) to indicate water count.

• Example in covalent compounds where the name reflects the number of each atom.

  • e.g., S2O4 is disulfur tetroxide. No prefix for 'one' on the first element.

Acids Naming Rules

• Binary Acids (contain hydrogen): use 'hydro' prefix + nonmetal + 'ic acid'.

  • Examples include hydrobromic acid from hydrogen and bromine.

• Oxyacids (contain polyatomic ions): named based on the polyatomic ion without 'hydro'.

  • Examples: nitric acid from nitrate, nitrous acid from nitrite.

• Importance of memorizing polyatomic ions for accurate naming.

Molar Mass and Compounds

• Molar mass is essential for converting grams to moles for compounds:

  • Use the total molar mass of the compound in grams per mole.

• Understand dimensional analysis:

  • Grams -> moles using molar mass.

  • Moles -> molecules using Avogadro's number (6.022 x 10^23).

• Determine number of atoms per molecule by counting individual atoms in the formula.

  • Example: Sodium phosphate contains 8 atoms (3 sodiums + 1 phosphate + 4 oxygens).

• Understanding how to find how many specific ions or atoms are in the compound.

Percent by Mass Calculation

• Percent by mass formula: (part/whole) x 100%.

• Example with sodium in sodium phosphate involves calculating sodium mass and dividing by total mass.

Empirical and Molecular Formulas

• Two-part question format in tests:

  • Find empirical formula from given percentages (assume 100g total).

  • Convert mass to moles using atomic weights, then find the simplest whole number ratio.

Chapter 5: Drawing Lewis Dot Structures

• Need to understand octet rule and valence electrons to draw accurate Lewis structures.

• Necessity to calculate electronegativity for bond type determination.

• Recognize types of bond characters based on electronegativity differences.

Bond Length and Energy

• Bond length hierarchy: Triple < Double < Single

• As atomic radii increase down a group, bond length also increases.

• Bond energy needed to break the bond follows opposing trends: Short bonds require more energy than long bonds.

Chapter 6: Hybridization

• Count groups around the central atom (bonded atoms and lone pairs) for hybridization.

• Identification of sigma and pi bonds:

  • First bond is sigma.

  • Additional bonds (like double or triple) include pi bonds as well.

Molecular Orbital Theory

• Charts provided for determining paramagnetism/diamagnetism and calculating bond order:

  • Bond order = (Bonding electrons - Antibonding electrons) / 2.