Light

EM spectrum, low → high energy: Radio · Microwave · Infrared · Visible · UV · X-ray · Gamma
Raging Martians Invaded Venus Using X-ray Guns

Visible: 400 nm (violet) to 700 nm (red).

See-saw: ν ↑ → λ ↓ · E ↑ → λ ↓ · E and ν rise together. Short wave = high energy.

Constants: c = 3.00×10⁸ m/s = 3.00×10¹⁷ nm/s · h = 6.626×10⁻³⁴ J·s · 1 mol = 6.022×10²³

c = λνE = hνE = hc/λ

Calc recipe: 1) nm → m: ×10⁻⁹ 2) rearrange, plug in 3) J → kJ/mol: × 6.022×10²³ ÷ 1000

Ground = lowest energy; excited = e⁻ bumped up. Absorption: photon in, e⁻ up. Emission: e⁻ down, light given off. Current model: quantum mechanical (electron cloud).

Quantum numbers & orbitals

n energy level (1–7) · ℓ sublevel → shape · m_ℓ orientation · m_s spin ±½

sublevel	s	p	d	f
orbitals	1	3	5	7
max e⁻	2	6	10	14

Level n has n sublevels: 1: s · 2: s, p · 3: s, p, d · 4: s, p, d, f

Aufbau: lowest energy first. Pauli: max 2 per box, ↑↓. Hund: one ↑ per box before pairing.
Aufbau or Hund broken = excited state. Pauli broken = impossible.

Configurations & ions

Fill order: 1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s 5f 6d 7p

Row = n. d block = row − 1. f block = row − 2. Noble gas shorthand: [noble gas above] + the rest.

Valence e⁻ = highest energy level (outer s + p). Transition metals: outer s.

Group	1	2	13	14	15	16	17	18
Valence	1	2	3	4	5	6	7	8
Ion	+1	+2	+3	±4	−3	−2	−1	none

Trap: transition metals lose 4s before 3d. Co = [Ar] 4s² 3d⁷ → Co²⁺ = [Ar] 3d⁷

Periodic trends

Coulombic attraction = pull between + nucleus and − electrons. Across →: more protons, same level, stronger pull. Down ↓: more levels and shielding, weaker pull.

Trend	Across →	Down ↓	Highest
Radius	shrinks	grows	bottom left
Ionization E	rises	drops	top right (He)
Electroneg.	rises	drops	top right (F)

Free response: 1) what changes (protons or levels) 2) stronger or weaker pull 3) the result.