Chord (music) Study Guide

📖 Core Concepts Chord – Two or more notes sounded together (simultaneous harmony). Arpeggio – A “broken” chord; its notes are played one after another. Chord progression – An ordered series of chords that moves toward a musical goal (e.g., tonic reinforcement or modulation). Homophonic texture – A single melody with chordal accompaniment moving in the same rhythm. Figured bass – Bar‑Baroque shorthand: numbers under a bass note tell which chord tones to add. Dominant‑seventh chord – A major triad + a minor seventh; creates strong pull to the tonic. Triad components – Root, third, fifth. Triad quality – Determined by the third (major = M3, minor = m3) and the fifth (perfect, diminished, augmented). Extended chords – Stack additional thirds above a triad: 7th, 9th, 11th, 13th. Inversions – Change which chord tone is in the bass (root‑position, 1st, 2nd, 3rd for seventh chords). Notation systems – Alphabetical (C, G♯7), Roman numerals (I, ii, V), Nashville numbers (1, 4, 5). Functional harmony – Tonic (rest), Subdominant (pre‑dominant), Dominant (tension → resolution). Voice leading in V⁷ – The tritone resolves stepwise: 7 ↓ ½ → 3 of I, 3 ↑ ½ → 1 of I. Borrowed & altered chords – Borrowed: from the parallel key; Altered: chromatically changed tones that mask the root. Jazz extensions – 9th, 11th, 13th chords, often with altered tones for colour. --- 📌 Must Remember Triad formula: Root‑Major/Minor‑Perfect/Diminished/Augmented fifth. Major vs. minor triad: Major = root‑M3‑P5; Minor = root‑m3‑P5. Dominant‑seventh resolution: \(\text{♭7} \downarrow \frac12\) → tonic third; \(\text{leading tone} \uparrow \frac12\) → tonic root. Inversion order: Root position: R in bass. 1st inversion: 3 in bass. 2nd inversion: 5 in bass. 3rd inversion (7th chords): 7 in bass. Roman numeral case: Uppercase = major quality, lowercase = minor quality. Nashville numbers transpose automatically: “1–4–5” works in any key. Extended chord building: Add successive thirds → 7 → 9 → 11 → 13, then the cycle returns to the root. Voice‑leading rule for V⁷: Both tritone notes move in opposite directions (resolution by half‑step). --- 🔄 Key Processes Building a basic triad Identify root. Add a third (major = 4 semitones, minor = 3). Add a fifth (perfect = 7 semitones; diminish = 6, augment = 8). Stacking extensions From a triad, add the seventh (major = 11, minor = 10). Continue adding thirds: 9th (14), 11th (17), 13th (21) semitones above the root. Figured‑bass realization Read bass note. Apply numbers (e.g., “6” = add a 6th above the bass; “♭3” = lower the third). Roman‑numeral analysis Determine scale degree of each chord root. Assign quality (uppercase/lowercase). Mark inversions with figures (e.g., V⁶, V⁶₄). Voice leading in a V⁷–I resolution Identify tritone (♭7–3). Resolve ♭7 down a half step to the tonic’s third. Resolve the leading tone up a half step to the tonic’s root. --- 🔍 Key Comparisons Major triad vs. Minor triad Third interval: M3 (4 semitones) vs. m3 (3 semitones). Sound: Bright/ happy vs. dark/ sad. Diminished vs. Augmented triad Fifth: Diminished = lowered 5th (♭5, 6 semitones); Augmented = raised 5th (#5, 8 semitones). Root‑position vs. 1st inversion Bass note: Root vs. third. Bass movement: Root‑position gives stable foundation; 1st inversion smooths bass line. Alphabetical notation vs. Roman numeral analysis Alphabetical: Shows absolute root (C, F♯). Roman: Shows functional role within a key (I, ii, V). Borrowed chord vs. Altered chord Borrowed: Same pitch set as parallel key, no modulation. Altered: Chromatically modified tones that obscure the root. --- ⚠️ Common Misunderstandings “All chords are built on thirds.” – True for triads and extensions, but tone clusters use seconds, not thirds. “A dominant‑seventh always resolves to the tonic.” – It strongly wants to, but can resolve to a deceptive target (e.g., vi). “Roman numeral “V” always means a major chord.” – In minor keys, V is often major (raised leading tone) or minor (natural minor). “Inversions change chord quality.” – Inversions only change bass note; the chord quality remains the same. “Jazz extensions always include the 7th.” – True for 9th, 11th, 13th chords in functional jazz; some pop “add9” chords omit the 7th. --- 🧠 Mental Models / Intuition “Stacked thirds = extended harmony.” Visualize a ladder: each rung is a third higher → seventh, ninth, etc. “Tension → Resolution”: Dominant = “pull”; tonic = “rest”. Picture a rubber band stretched (V) snapping back to home (I). “Inversion as bass line smoothing.” Imagine walking up stairs: staying on the same step (root) feels jumpy; shifting to the next step (3rd) makes the walk smoother. --- 🚩 Exceptions & Edge Cases V in minor keys – Often raised leading tone creates a major‑quality V (V) rather than minor (v). Polychords – Two independent chords sounding together; not simply a thickened triad. Tone clusters – Built from seconds; they defy the “stacked thirds” rule. Borrowed chords – Can appear without a full key change (e.g., iv in major). --- 📍 When to Use Which Alphabetical vs. Roman vs. Nashville Use alphabetical for real‑time pop/jam sessions where key is fixed. Use Roman for analytical writing or classical theory exams. Use Nashville when you need to transpose on the fly (e.g., studio work). Triad vs. extended chord Choose a triad for simple harmonic support (folk, early classical). Choose an extended (7th/9th/13th) for richer colour (jazz, modern pop). Borrowed vs. altered Borrowed chords add modal colour while staying diatonically recognizable. Altered chords create strong chromatic tension; use when you want “outside” sound or strong voice‑leading pull. --- 👀 Patterns to Recognize I–V–I or I–IV–V–I = classic tonal reinforcement. Dominant‑seventh tritone always appears as ♭7–3 (e.g., B♭–E in G⁷). Extended chords often notated with “9”, “11”, “13” after the root (e.g., C13). Inversions flagged by slash notation or figures: C/E (1st inversion), C/G (2nd). Jazz charts: “Δ” = major‑7, “♭9” = flat ninth alteration, “♯11” = sharp eleventh. --- 🗂️ Exam Traps Mistaking “♭3” in figured bass for a minor third – It actually means lower the third relative to the bass note, not change the chord quality. Assuming any “7” chord is dominant – “C7” is a dominant‑seventh (major triad + minor 7); “CΔ7” (or “Cmaj7”) is a major‑seventh (different function). Confusing borrowed iv with a modulation to the parallel minor – Borrowed chord stays in the original key; a true modulation would shift the tonal centre. Reading “13” as a thirteenth only – It implies a 7th and 9th are present unless otherwise indicated (e.g., “13(no5)”). Over‑applying voice‑leading rule to non‑dominant sevenths – The tritone resolution rule specifically applies to dominant‑seventh chords, not to, say, a minor‑7 built on the subdominant. ---