DV

Weekly challenges, grading, and nomenclature notes

Weekly challenges, regrades, and course expectations

  • Regrade policy (as stated): the regrade component is the sum of two columns and contributes to the final grade alongside weekly challenges.
  • Weekly challenges: there are seven challenges total; the system (Brightspace) can auto-drop one weekly challenge.
    • Policy: you count your best six out of seven weekly challenges.
    • If there is only a single weekly challenge score present (e.g., only Weekly Challenge 1 is available), that one can be dropped by the system, effectively removing it from the calculation.
    • Practical implication: you should aim to complete multiple early challenges to avoid a situation where an early drop harms your final score.
  • Grading thresholds and curves (as explained):
    • The 50% path is mentioned; this is described as the target/threshold understood for progression.
    • 60% is a C-.
    • There is no curve in M104 (no curved grading policy is used).
    • The message emphasizes that this is not high school-level grading, and absolute performance matters for the course.
  • Group work and preparedness for discussions:
    • Know your section number and your group number.
    • For tomorrow night’s discussion, students are encouraged to come prepared.
    • Do not rely entirely on group members to bring materials (notes, calculators, etc.).
    • Prior experience: some students rely on the group to supply notes and tools, which can leave others unprepared; this is discouraged to promote individual accountability.
  • Reminder about the structure of the second element in naming (context for later chemistry topics):
    • The second name uses a suffix
      -ide (e.g., binary molecular compounds).
    • There’s a note that there is no difference in naming between molecular compounds and ionic contexts for this particular convention.
    • When more than one unit of an element is present (or even when there is one of some components), number prefixes are used; there is an exception noted: if the first element is present in only one quantity, you don’t include the prefix for the first element. If the second element is present in only one quantity, you do include the prefix for the second element. If the first element is present in more than one, you include the prefix for the first element.
  • Put another way: prefixes are used for both elements unless the first element is present in a single amount; the second element’s prefix usage follows the same logic with the caveat described above.
  • Overall emphasis: be prepared, participate actively, and follow the course policies (drop policy, no curve, etc.).

Nomenclature: general concepts and rules

  • Key idea: when naming compounds, observe the suffix for the second element and use prefixes to indicate the quantity of each element when needed.
  • The base rule: for binary compounds, the second element typically ends with the suffix -ide.
  • Prefix usage (as described in the transcript):
    • You need prefixes for both elements unless the first element has only one atom (in which case you don’t use a prefix for the first element).
    • If the second element has more than one atom, you include a prefix for the second element; if it has only one, you still include the prefix according to the speaker’s note (though in standard naming convention, mono- is often omitted for the first element and used for the second when necessary).
  • Context: this section distinguishes between molecular covalent naming and ionic naming for the case described, and notes the important role of prefixes in conveying quantity.

Group trends and known charges in main-group elements

  • Main-group elements (groups 17, 16, 15, 14) have known typical charges used in naming and formula assignment in this unit.
  • Practical takeaway: familiarity with expected oxidation states helps determine formula composition and naming conventions for polyatomic ions and binary compounds.

Carbamate and carboxylate concepts (structure and bonding)

  • Carbamate-related discussion highlights polar bonds within a carbamate molecule.
  • The structure is described as having two additional electrons to make bonding work (an interpretation of electron accounting to satisfy valence and resonance in the carbamate framework).
  • Carboxylate group: presented as a relevant functional group in organic/inorganic chemistry discussions (resonance stabilization is often implicit in carboxylate chemistry).
  • Significance: these groups influence reactivity, resonance stabilization, and how bonds are depicted in Lewis or resonance forms.

Ion series: -ate versus -ite and oxygen-removal concept

  • Concept: removing one oxygen from an -ate ion yields the -ite form, with the charge staying the same.
    • Examples:
    • Nitrate NO₃⁻ (ate) → Nitrite NO₂⁻ (ite)
    • Sulfate SO₄^{2-} (ate) → Sulfite SO₃^{2-} (ite)
    • Chlorate ClO₃⁻ (ate) → Chlorite ClO₂⁻ (ite)
  • Phosphate vs phosphite (illustrative of the same idea):
    • Phosphate: ext{PO}_4^{3-}
    • Phosphite: ext{PO}_3^{3-}
  • Takeaway: the -ate to -ite transformation preserves the overall charge but reduces the number of oxygens by one.

Binary acids and polyatomic acids: naming patterns

  • Binary acids (hydrogen + another element):
    • The naming convention uses the hydro- prefix derived from hydrogen.
    • Acid form example: H₂S is named hydrosulfuric acid; HCl is hydrochloric acid.
    • Note in the transcript: the acid form is given as hydrosulfuric acid for H₂S, illustrating the hydro- prefix usage in binary acids.
  • Polyatomic acids (derived from polyatomic ions):
    • If the ion ends in -ate, the corresponding acid name changes the suffix from -ate to -ic and appends the word “acid” (without adding hydro).
    • Example: nitrate NO₃⁻ → nitric acid HNO₃; sulfate SO₄^{2-} → sulfuric acid H₂SO₄.
    • If the ion ends in -ite, the suffix becomes -ous and adds “acid.”
    • Example: nitrite NO₂⁻ → nitrous acid HNO₂; chlorite ClO₂⁻ → chlorous acid HClO₂.
  • Charge context: many polyatomic ions in these contexts carry a -1 charge (e.g., NO₃⁻, NO₂⁻, ClO₃⁻, ClO₂⁻, ClO⁻, etc.).
  • Examples with specific ions mentioned or implied in the transcript:
    • Chlorate, chlorite, hypochlorite correspond to ClO₃⁻, ClO₂⁻, ClO⁻ respectively, with acids formed as chloric acid, chlorous acid, hypochlorous acid (following the -ate → -ic and -ite → -ous rules for polyatomic acids).
    • Phosphate family: PO₄^{3-} (phosphate) and PO₃^{3-} (phosphite) illustrate the same “ate vs ite” theme in a non-sulfur context and are common reference points for discussing polyatomic acid formation from oxyanions.

Summary of key formulas and examples

  • Final grade composition (example formula based on transcript description):
    • Let weekly scores be w1, w2, ldots, w7 and regrade contributions be r1, r_2.
    • Final grade contribution from weekly challenges: G{ ext{weeks}} = ext{max}{S \,:\, |S|=6} igg( igg[igwedge{i \,in\,S} wiigg] igg)
    • Total final grade: G = G{ ext{weeks}} + r1 + r_2
  • Polyatomic ions (examples):
    • ext{NO}3^{-}, ext{NO}2^{-}, ext{SO}4^{2-}, ext{SO}3^{2-}, ext{ClO}3^{-}, ext{ClO}2^{-}, ext{ClO}^{-}
  • Acids naming patterns:
    • Binary acid examples: HCl → hydrochloric acid; H₂S → hydrosulfuric acid.
    • -ate to -ic, -ite to -ous in polyatomic acids:
    • ext{NO}3^{-} ightarrow ext{HNO}3 ext{ (nitric acid)}
    • ext{NO}2^{-} ightarrow ext{HNO}2 ext{ (nitrous acid)}
    • ext{SO}4^{2-} ightarrow ext{H}2 ext{SO}_4 ext{ (sulfuric acid)}
    • ext{SO}3^{2-} ightarrow ext{H}2 ext{SO}_3 ext{ (sulfurous acid)}
    • ext{ClO}3^{-} ightarrow ext{HClO}3 ext{ (chloric acid)}
    • ext{ClO}2^{-} ightarrow ext{HClO}2 ext{ (chlorous acid)}
  • Common ions and charges (quick reference):
    • ext{NO}3^{-} ext{(nitrate)}, ext{NO}2^{-} ext{(nitrite)}
    • ext{SO}4^{2-} ext{(sulfate)}, ext{SO}3^{2-} ext{(sulfite)}
    • ext{ClO}3^{-}, ext{ClO}2^{-}, ext{ClO}^{-} ext{(chlorate, chlorite, hypochlorite)}

Practical study tips and caveats

  • Expect Brightspace or the LMS to auto-drop one weekly challenge; plan to complete at least six challenges to secure a solid score.
  • Do not rely solely on group work for discussions; come prepared with notes and materials to avoid disadvantaging yourself or others.
  • For nomenclature, be careful with prefix usage and the -ide suffix for the second element in binary compounds; remember the potential ambiguity in the transcript about when prefixes are required for first vs second elements, and consult standard course materials or instructor guidance if in doubt.
  • For acid naming, memorize the hydro- prefix usage for binary acids and the -ate -> -ic and -ite -> -ous rules for polyatomic acids; practice with common ions to solidify the patterns.
  • Connect these topics to foundational ideas: grading policies connect to course logistics and assessment design; nomenclature connects to oxidation states, electron counting, and resonance concepts that underpin inorganic chemistry.

Note: Some parts of the transcript include phrasing that is slightly ambiguous or idiosyncratic (e.g., specific rules for when prefixes are used in naming). The notes above present both the exact statements from the transcript and the standard conventions where applicable. If you have a rubric or a cheat sheet from your instructor, align these notes with those guidelines for your exam preparation.