CHEM 120 · Test 2 — Last Look Modules 2–4 · formulas only
17 Q · 45 min · bubble sheet (fill version #) · assigned seat. Module 2 → 6 Q (§2.4 Bohr→end) · Module 3 → 6 Q (all) · Module 4 → 5 Q (p1–14: Lewis + resonance only). NOT tested: Mod 1 stoich · Mod 4 VSEPR/polarity/lattice · all Mod 5.
GIVEN on data sheet
Periodic table (molar masses + Z)
R_H=2.179×10⁻¹⁸ · h=6.626×10⁻³⁴ · c=2.998×10⁸
N_A · mₑ · e · π
c=λν · E=hν · λ=h/p · p=mv · KE=½mv²
Eₙ=−R_H/n² · ΔE=−R_H(1/n_f²−1/n_i²)
MEMORIZE (not given)
a₀ = 52.9 pm (1s r_mp)
Heisenberg: Δx·Δp ≥ h/4π
node rules · RDF=4πr²R² · Aufbau order · trends · octet/FC/resonance rules
QUANTUM — M2 6 Q
λ = hc/|ΔE| λ_dB = h/(mv)
Bohr: n=1 ground; E<0; levels converge as n↑. drop=emit(ΔE<0), jump=absorb.
QN: n size · ℓ shape(0s1p2d3f) · mₗ(−ℓ..+ℓ) · mₛ ±½. ℓ≤n−1, |mₗ|≤ℓ.
For H, energy on n only (3s=3p=3d).
NODES / ORBITALS — M2 ⭐
| # orb level n | n² |
| angular nodes | ℓ |
| radial nodes | n−ℓ−1 |
| total nodes | n−1 |
| maxima R²/RDF | n−ℓ |
R-vs-r: max@0 → s; 0@0 → p/d/f. crossings = radial nodes. +/− = phase (not charge).
CONFIGS / TRENDS — M3 6 Q
Fill (n+ℓ):
1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s…
Cr=[Ar]4s¹3d⁵ Cu=[Ar]4s¹3d¹⁰
Cations: strip highest-n first (ns before d) → Mn²⁺=[Ar]3d⁵
Pauli · Aufbau · Hund · shell max=2n² · s<p<d<f
| →period | ↓group |
|---|
| radius | ↓ | ↑ |
| IE / EA / EN | ↑ | ↓ |
IE dips: Be→B, N→O · F EN=4.0 · diamag=all paired
LEWIS + RESONANCE — M4 5 Q
valence e⁻ = Σval − charge (add for anion)
FC = val − (lp + ½bond)
ΣFC = charge · −FC on more-EN atom · smallest FC wins
H terminal · C/N/O/F ≤ octet · period 3+ expand (S,P,Cl,Br,I,Xe) · central = least-EN
Resonance: move π & lone pairs only (never σ); needs ≥1 double/triple bond; real = hybrid avg
Nitrate N FC=+1 · term. −O FC=−1
FOUNDATION (assumed)
Light: c=λν, E=hν=hc/λ. EM: radio→micro→IR→vis 400–750nm→UV→X→γ (λ↓,E↑).
3 experiments: Blackbody (E=n·hν) · Photoelectric (photons, threshold ν; hν=w+½mv²) · Line spectra (quantized).
Valence e⁻ = group# (1–2) or group#−10 (13–18). Lewis symbol = dots. EN rises top-right: F>O>N≈Cl.
Ionic = metal+nonmetal · molecular = 2 nonmetals. Know polyatomic ions (NO₃⁻,SO₄²⁻,CO₃²⁻,NH₄⁺,OH⁻,PO₄³⁻…).
DON'T-FORGET TRAPS
• angular=ℓ, radial=n−ℓ−1 (not swapped)
• a₀ & Heisenberg NOT on data sheet — memorize
• cations: 4s off before 3d (Mn²⁺=[Ar]3d⁵)
• IE dips Be→B & N→O (explain by config)
• resonance major: more-EN atom holds −charge (not "smaller FC")
• ℓ ≤ n−1 for a valid quantum-number set