Harmony: Triads and Chords Cheat Sheet

The core ideas of Harmony: Triads and Chords distilled into a single, scannable reference — perfect for review or quick lookup.

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Quick Reference

Triad Construction

A triad is a three-note chord built by stacking two thirds above a root note. The four triad qualities are major (M3+m3), minor (m3+M3), diminished (m3+m3), and augmented (M3+M3). Each quality has a distinctive sound character.

Seventh Chord Types

A seventh chord adds a fourth note a third above the fifth of a triad. The five common types are: major 7th (M3+m3+M3), dominant 7th (M3+m3+m3), minor 7th (m3+M3+m3), half-diminished 7th (m3+m3+M3), and fully diminished 7th (m3+m3+m3).

Chord Inversions

A chord inversion occurs when a note other than the root is the lowest-sounding pitch (bass note). Root position has the root in the bass. First inversion has the third in the bass. Second inversion has the fifth in the bass. Seventh chords also have third inversion with the seventh in the bass.

Figured Bass Notation

Figured bass uses numbers below a bass note to indicate the intervals above it, specifying chord inversions. Root position triad = 5/3 (often no figures). First inversion = 6/3 (written as 6). Second inversion = 6/4. For seventh chords: root = 7, first = 6/5, second = 4/3, third = 4/2 (or 2).

Diatonic Triads and Roman Numerals

Diatonic triads are chords built using only the notes of a given key. In Roman numeral analysis, uppercase numerals indicate major triads and lowercase indicate minor triads. A degree symbol indicates diminished and a plus sign indicates augmented.

Diatonic Seventh Chords

Diatonic seventh chords are four-note chords built on each scale degree using only notes from the key. Each scale degree produces a specific seventh chord quality, creating a unique set of sounds for major and minor keys.

Harmonic Function: Tonic, Predominant, Dominant

Every diatonic chord serves one of three harmonic functions. Tonic chords (I, vi, iii) provide stability and rest. Predominant chords (IV, ii) create momentum toward the dominant. Dominant chords (V, vii-dim) create tension that resolves to the tonic.

Chord Quality and Interval Stacking

Chord quality is determined by the specific combination of intervals stacked from the root. By knowing the interval structure, you can build any chord quality from any root note without memorizing every individual chord.

Key Terms at a Glance

Triad:A three-note chord built by stacking two thirds above a root note. The four qualities are major, minor, diminished, and augmented.

Root:The foundational note of a chord from which the other notes are measured. The root gives the chord its letter name.

Major Triad:A triad consisting of a major 3rd and a minor 3rd stacked from the root, producing a bright, stable sound.

Minor Triad:A triad consisting of a minor 3rd and a major 3rd stacked from the root, producing a darker, more somber sound.

Diminished Triad:A triad consisting of two minor 3rds stacked from the root, producing a tense, unstable sound with a diminished 5th.

Augmented Triad:A triad consisting of two major 3rds stacked from the root, producing a bright, unstable sound with an augmented 5th.

Seventh Chord:A four-note chord built by adding a third above the fifth of a triad. The five common types are major 7th, dominant 7th, minor 7th, half-diminished 7th, and fully diminished 7th.

Dominant Seventh:A chord consisting of a major triad plus a minor 7th interval. It occurs naturally on scale degree 5 and has a strong tendency to resolve to the tonic.

Major Seventh:A chord consisting of a major triad plus a major 7th interval. It occurs on scale degrees 1 and 4 in major keys and has a lush, jazzy sound.

Half-Diminished Seventh:A chord consisting of a diminished triad plus a minor 7th interval. It occurs on scale degree 7 in major keys and scale degree 2 in minor keys.

Inversion:A chord arrangement where a note other than the root is the lowest-sounding pitch. First inversion has the 3rd in the bass; second inversion has the 5th in the bass.

Root Position:A chord voicing in which the root is the lowest-sounding note. Figured bass: 5/3 (or no figures).

Figured Bass:A notation system using numbers below a bass note to indicate intervals above it, specifying chord inversions and voice leading.

Roman Numeral Analysis:A system for labeling chords by their scale degree and quality, using uppercase for major and lowercase for minor, enabling key-independent harmonic analysis.

Diatonic:Using only the notes that belong to a given key or scale, without chromatic alterations.

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