Unit 3: Music Fundamentals III: Triads and Seventh Chords

Chord

A collection of multiple pitches that sound at the same time and form a single harmonic idea.

Stacking thirds

A common-practice method of building harmony by placing chord tones a third apart above a starting note to form triads and seventh chords.

Root

The pitch a chord is built on (the bottom note when the chord is stacked in thirds), even if it is not the lowest-sounding note.

Root vs. bass

The root is the chord’s foundational pitch (found by stacking in thirds); the bass is simply the lowest-sounding note and may be a different chord member in inversions.

Letter-name spacing

The rule that interval size is determined by letter names first (a third means “skip one letter,” e.g., C to E), regardless of accidentals.

Interval quality (semitone distance)

The quality of an interval (major, minor, diminished, etc.) determined by the exact number of semitones once the correct letter names are in place.

Chord spelling

Writing chord tones with correct letter names and accidentals (not just “correct-sounding” pitches), which matters for AP scoring.

Diatonic chords

Chords derived only from the notes of a particular key’s scale; there are seven diatonic chords in each key (one per scale degree).

Scale degree

A note’s position in a key’s scale (1 through 7), used to identify chord roots for Roman numeral analysis.

Triad

A three-note chord built from two stacked thirds.

Chord members (triad)

The functional tones within a triad: root, third (a third above the root), and fifth (a fifth above the root).

Root position

A chord position in which the root is the lowest-sounding note.

Inversion

Any chord position where a chord member other than the root is in the bass, changing the sound and aiding smoother voice leading.

First inversion (triads)

A triad inversion with the third in the bass.

Second inversion (triads)

A triad inversion with the fifth in the bass.

Figured bass

A system using a bass note with Arabic numbers that show the intervals above the bass to be played; it indicates inversion and required chord intervals.

5/3

The root-position triad figure (often omitted), indicating a third and a fifth above the bass.

6 (6/3)

The first-inversion triad figure, indicating a third and a sixth above the bass.

6/4

The second-inversion triad figure, indicating a fourth and a sixth above the bass.

Roman numeral analysis

A key-based system that labels chords by the scale degree of the root, chord quality, and inversion (using figured bass numbers).

Roman numeral quality conventions

Uppercase = major; lowercase = minor; diminished uses ° (e.g., vii°); augmented uses + when appropriate (e.g., III+).

Tonic function

A harmonic function that feels like rest/home/stability (often I, sometimes vi or iii).

Predominant function

A harmonic function that moves away from tonic and prepares dominant (often ii or IV).

Dominant function

A harmonic function that creates tension needing resolution to tonic (especially V and vii°).

Major triad

A triad with a major third and a perfect fifth above the root (equivalently: major third + minor third stacked).

Minor triad

A triad with a minor third and a perfect fifth above the root (equivalently: minor third + major third stacked).

Diminished triad

A triad with a minor third and a diminished fifth above the root (equivalently: minor third + minor third stacked).

Augmented triad

A triad with a major third and an augmented fifth above the root (equivalently: major third + major third stacked).

Natural minor

The basic minor scale form; its diatonic triads include v (minor) and VII (major), and scale-degree 7 is a subtonic (not a leading tone).

Harmonic minor

A minor-scale form that raises scale-degree 7 to create a leading tone, commonly producing a major V and leading-tone diminished chords (vii°/vii°7).

Melodic minor

A minor-scale form that often raises scale-degrees 6 and 7 (context-dependent), affecting chord qualities in minor keys.

Subtonic

Scale-degree 7 in natural minor, located a whole step below the tonic; the VII triad built on it is typically major.

Leading tone

Raised scale-degree 7 (in major and harmonic/melodic minor) that strongly tends to resolve up by step to scale-degree 1.

Dominant in minor (raised 7)

The common-practice approach of using harmonic-minor influence so V (and V7) in minor is major (or dominant seventh) by raising scale-degree 7 to create a leading tone.

Seventh chord

A four-note chord built by stacking three thirds; it includes root, third, fifth, and seventh and is generally less stable than a triad.

Chordal seventh

The note that forms a seventh above a seventh chord’s root; in common-practice voice leading it typically resolves down by step.

Major-major seventh chord

A seventh-chord quality: major triad plus a major seventh above the root (often called “major seventh”).

Dominant seventh chord (quality)

A specific seventh-chord quality: major triad plus a minor seventh above the root (not merely “a seventh chord on V”).

Minor-minor seventh chord

A seventh-chord quality: minor triad plus a minor seventh above the root (often called “minor seventh”).

Half-diminished seventh chord

A seventh-chord quality: diminished triad plus a minor seventh above the root; notated with ø (e.g., viiø7).

Fully diminished seventh chord

A seventh-chord quality: diminished triad plus a diminished seventh above the root; very tense and common on the leading tone in harmonic minor.

Diatonic seventh chords in major (pattern)

The standard diatonic pattern in major: I7 and IV7 = major-major; ii7/iii7/vi7 = minor-minor; V7 = dominant seventh; viiø7 = half-diminished.

viiø7 (in major)

The diatonic seventh chord on scale-degree 7 in a major key; it is half-diminished and often functions like dominant harmony.

Seventh-chord inversions

Inversions of seventh chords (root, third, fifth, or seventh in the bass) used frequently to smooth voice leading and bass motion.

7 (root-position seventh chord figure)

The figured-bass/inversion label for a seventh chord in root position.

6/5

The figured-bass/inversion label for a seventh chord in first inversion (third in the bass).

4/3

The figured-bass/inversion label for a seventh chord in second inversion (fifth in the bass).

4/2 (or 2)

The figured-bass/inversion label for a seventh chord in third inversion (seventh in the bass).

Chord symbols (lead-sheet notation)

A naming system that labels chords by letter name and quality (e.g., Cm, C7, Cmaj7, Cø7), independent of key.

Slash chord

A chord symbol that specifies a particular bass note after a slash (e.g., C/E = C major with E in the bass), indicating inversion/bass choice.