Lewis Builder

#	Mode	Species	Budget	TOTAL drawn	AROUND each atom	Result
Press Record to keep a reading.

Investigations

1 · Count, connect, fill

Build PCl₃ with single bonds only, then SiCl₄. Check both counts on each, record, and read what the AROUND chips say about the central atom.

Predict first: after the three Cl atoms have their pairs, how many electrons of the 26 are left, and where do they go?

2 · When the budget runs out

Move a pair: O₂ first, then N₂. Record the counts before the first move and after the last one.

Predict first: how many pairs must move in for O₂, and how many for N₂? What does each move do to the TOTAL?

3 · The charge changes the budget

Build PH₄⁺, then BrO⁻. Check both, record both.

Predict first: PH₄⁺'s atoms bring 9 electrons and BrO⁻'s bring 13. What budget does each diagram actually show, and why?

4 · The splint test

In Move a pair, finish N₂ and read the bond graph; then finish O₂. Record both bonds.

The deck's question: which bond takes more energy to break, and by about how much? Does the diagram predict the measured number?

5 · Formal charge, atom by atom

In Formal charge, show CO and read the badge on each atom and the sum; then NO⁺ and CN⁻ (Topic 2.6 · Formal charge). Record all three.

Predict first: CO shares three pairs and gives each atom one lone pair. Which atom owns more electrons than it brought, by how many, and what must the two charges add up to?

6 · Choose the diagram

Compare CS₂ two ways, then NOBr two ways. Assign every charge yourself, pick the better model and the rule that decides it, check, record.

Predict first: both diagrams of CS₂ pass the two counts. What separates them, and which rule says so?

7 · The azide trio

Compare the three diagrams of N₃⁻. Which contributes most, and which two are equivalent? Check, record, then read the measured bond length in the verdict.

Predict first: every diagram of N₃⁻ carries charges. What does "closest to zero" mean when the magnitudes add to the same total?

8 · Ozone's two pictures

In Resonance, start from ozone's first structure: a pair out of the double bond, then a pair in from the other side. Record when the set is complete and read the hybrid and the bond-length bars.

Predict first: after the two moves, what has changed and what has not? What bond order does the hybrid give each O–O bond, and where does 128 pm sit between 121 and 148?

9 · The odd electron

Resonance, NO₂: 17 electrons and a single dot on N. Find the second structure and record; then show NO₂ in Formal charge.

Predict first: can moving pairs give the lone electron a partner? Which atom stays at 7, and which atom carries the +1?