Explicit science instruction
The week’s ideas form one chain: electron-count differences create ions, charge balance determines empirical ratios, and extended electrostatic attraction produces lattice-level properties.
A strong explanation moves between symbolic and particle representations. It can read MgCl₂ as a charge-balanced ratio, draw the alternating lattice conceptually, and predict why mobility changes conductivity.
Keep model limits explicit. Real materials can contain defects, hydration effects, mixed bonding, and temperature-dependent behavior.
Vocabulary: structure–property relationship; charge balance; lattice; evidence; limitation.
Worked example with reasoning
Claim: an unknown solid is consistent with an ionic lattice. Evidence: it is brittle, has high melting behavior, does not conduct as a solid, and conducts strongly when molten. Reasoning: fixed ions prevent solid conduction while mobile ions carry charge after melting.
Guided question
Write a CER that includes one formula audit and two structure–property observations.
Independent work
- Submit one charge-balanced formula set.
- Submit one lattice/property diagram.
- Write a CER with at least two property observations and one limitation.
- Record one correction from this week.
Spiral retrieval bridge
- From Week 05: why is K generally larger than Na?
- From Week 04: why do discrete spectral lines support quantized energy differences?
- From Week 03: calculate a two-isotope weighted average.
- From Week 02: distinguish direct observation from model inference.
Misconception check
Ionic compounds are not defined by being soluble in water; solubility varies with the balance of lattice and solvation interactions.
Formative understanding check
What makes a structure–property claim stronger than simply labeling a substance ionic?
Reveal response
It connects multiple measured properties to a coherent particle-level model and acknowledges alternatives or limits.
Public self-check only.
Mentor evidence conference
Ask Archaemenes to challenge your particle, charge, and evidence reasoning before you finalize the week record.
Teacher guidance
Foundation: Use a CER frame with a supplied formula and one property.
Core: Integrate formula, lattice, and multiple property observations.
Extended: Evaluate an ambiguous material and propose a discriminating test.
Return to Friday Evidence