Enhanced overlay: Weeks 1-2 bootcamp session-06.html may be taught with this lesson. The bootcamp is not the whole course.

Canonical lesson CHEMISTRY20-U1-L17 · outcome 20-A2.4k · depth ENHANCED_BOOTCAMP_OVERLAY

Unit A: Diversity of Matter and Chemical Bonding - outcome 20-A2.4k

• Course: CHEMISTRY20 (SCN2796)
• Lesson ID: CHEMISTRY20-U1-L17
• Official outcome: 20-A2.4k (KNOWLEDGE)
• Object type: canonical lesson (not a bootcamp session)
• Source: Alberta Chemistry 20 Program of Studies (2007, updated 2014)

Official outcome text

draw electron dot diagrams of atoms and molecules, writing structural formulas for molecular substances and using Lewis structures to predict bonding in simple molecules

Learning intention

Meet 20-A2.4k with instruction, practice, and a check. The 10-session bootcamp does not replace this lesson.

Success criteria

1. Restate the outcome in classroom language without swapping in a different unit’s template.
2. Complete the worked-style task for this outcome.
3. Name the lab setting (classroom-supervised / teacher demo / dataset or simulation / forbidden).

Teaching

Count valence electrons, place the least electronegative atom (often C) in the centre (H is never central), connect with single bonds, complete octets with lone pairs, then convert lone pairs to multiple bonds if needed. Structural formulas show bonds as lines. Lewis structures include lone pairs.

Worked example

H2O: 8 valence electrons, O central, two O-H singles, two lone pairs on O. CO2: 16 electrons, O=C=O, two lone pairs on each O. NH3: N with three H and one lone pair.

Guided practice

1. Lewis for CH2O (formaldehyde): C central. Do not copy H2O/CO2/NH3.
2. Near-miss: H2O drawn linear with no lone pairs. Mark the first wrong line.

Independent practice

1. Lewis for OF2.
2. Two sentences: why C is central in CO2 but H cannot be central in H2O.
3. Valence-electron inventory for CH2O.

Diagram / whiteboard

Approved diagram id chem20-ionic-lattice - Ionic lattice / bonding sketch. Tutor may open the course whiteboard and display this id. Do not invent hazardous procedures on the board.

Checks for understanding

Use the formative evidence below as the exit check for this outcome. Correct the misconception named in this lesson before praising.

Misconception to repair

Putting H in the centre, or expanding octet on C in Chem 20 simple molecules.

Safety and lab register

Setting: classroom-supervised only for Session 04 conductivity (NaCl / sucrose / ~5% vinegar, 9 V LED or school probe). All other Unit A work is paper, models, data cards, or approved simulation. Forbidden: bleach+acid, bleach+ammonia, flames, tasting, home copy of Session 04, concentrated acids/bases, generating Cl2. AI Tutor must not invent labs outside CHEM20_LOW_RESOURCE_LAB_REGISTER.csv.

Alberta Poison Control if a real exposure is occurring: 1-844-764-7669. The AI Tutor is not a poison centre.

Formative evidence

Lewis for H2O and CO2; state electron totals.

This is not a diploma. Mastery needs instruction + activity + check.

AI Tutor / human tutor

Ground on 20-A2.4k. No false praise. No invented procedures. No silent skip to a different unit. Human tutor if the student describes mixing bleach, tasting, or flames.

Provenance

Official POS wording from ALBERTA_SENIOR_HIGH_OFFICIAL_OUTCOMES.csv. Pack lesson written to replace Wave-4 contaminated canonical markdown.