Chords and Harmony (SACE Stage 2 Music)
“Construct and label triads and seventh chords, and explain how they function within a key using Roman numerals and figured bass”
A triad is three notes stacked in thirds (root, third, fifth) and comes in four qualities: major, minor, diminished and augmented. Adding another third on top makes a seventh chord. Roman numerals label each chord by its scale degree and quality, showing its function, while cadences (perfect, plagal, imperfect, interrupted) mark how phrases end.
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What this dot point is asking
You need to build and label any triad or seventh chord, identify its inversion, and explain how chords function inside a key. This connects directly to analysis and to harmonising melodies in composition.
Building triads
Take a root, add the note a third above, then the note a fifth above the root. The quality depends on the two stacked thirds:
- Major triad: major third then minor third (C E G).
- Minor triad: minor third then major third (C E flat G).
- Diminished triad: two minor thirds (C E flat G flat).
- Augmented triad: two major thirds (C E G sharp).
Harmonising each degree of a major scale gives a fixed pattern of qualities: I major, ii minor, iii minor, IV major, V major, vi minor, vii diminished. Upper-case Roman numerals mean major, lower-case mean minor, and a small circle marks the diminished chord. This pattern lets you label chords instantly once you know the key.
Seventh chords
Adding a fourth note a third above the fifth makes a seventh chord. The most important is the dominant seventh (V7), built on the fifth degree: a major triad plus a minor seventh (G B D F in C major). Its built-in tritone (between the third and seventh) creates strong pull back to the tonic, which is why V7 to I is the most decisive progression in tonal music. Other common types are the major seventh, minor seventh and half-diminished seventh.
Inversions and figured bass
When a note other than the root is in the bass, the chord is inverted. Figures show this:
- Root position (5/3), often unmarked.
- First inversion (6/3, usually just 6): the third is in the bass.
- Second inversion (6/4): the fifth is in the bass.
For seventh chords the figures are 7, 6/5, 4/3 and 4/2 for root position through to third inversion. Roman numerals combine with these figures, so a first-inversion tonic in C is written I6 (or Ib).
Function and progression
Chords group into functions. The tonic (I, and often vi) gives stability and rest. The dominant (V, V7, vii) creates tension that wants to resolve to the tonic. The subdominant or pre-dominant (IV, ii) moves the music away from the tonic and sets up the dominant. A huge amount of tonal music follows the path tonic to pre-dominant to dominant to tonic.
Cadences
A cadence is the harmonic punctuation at the end of a phrase:
- Perfect (authentic): V to I, a full stop.
- Plagal: IV to I, the gentle amen.
- Imperfect (half): ends on V, a comma that needs continuation.
- Interrupted (deceptive): V to vi, a surprise that avoids the expected resolution.
Recognising cadences by ear and on the page is a common aural and analysis task.
Step 1: Stack the notes into thirds to find the root
Take the printed chord, for example the notes A, C and F in the key of C major. Reorder them into a stack of thirds (F, A, C) so the lowest note of the stack, F, is the root. The chord is built on F regardless of which note is in the bass.
Step 2: Find the scale degree and quality
F is the fourth degree of C major, and the stack F A C is a major triad, so the chord is IV. Upper-case confirms it is major.
Step 3: Read the bass note to find the inversion
The actual bass note is A, the third of the chord, so this is a first inversion. Combine the numeral and figure: IV6 (or IVb). Naming root, quality and inversion separately, in that order, gives the full label every time.
A C major chord with E in the bass is still chord I in C major (in first inversion), not chord iii. The Roman numeral comes from the root, not the lowest sounding note. Identify the root by reordering the notes into a stack of thirds first, then read the bass note separately to find the inversion. Mislabelling inversions as different chords wrecks both your analysis and any harmonisation you write.
Why this matters
Harmony underpins the whole course. In analysis you label progressions and cadences to explain how a piece is organised. In composition and arranging you choose chords to support a melody and create direction. In the aural test you must hear whether a chord is major or minor and whether a cadence is perfect or interrupted. Drill triad qualities in every key, then practise hearing I, IV and V in real recordings until the functions are obvious.
Exam-style questions
Questions in the style of SACE Board exam questions on this dot point, each with a worked answer. They are written by ExamExplained unless tagged "Past paper"; the year shows the paper a question is modelled on.
2024 SACE Stage 2-style1 markAn example will be played three times. Tick the appropriate box to indicate which type of chord is played: Diminished triad, Major triad, Minor triad, or Augmented triad.Show worked answer →
One mark for the correct triad quality. The four options differ only in the size of their two stacked thirds, so identify the chord by its sound and interval structure.
Major triad: major 3rd then minor 3rd (root, +4 semitones, +3), bright and stable. Minor triad: minor 3rd then major 3rd (root, +3, +4), darker but stable. Diminished triad: two stacked minor 3rds (+3, +3), tense and unstable with a diminished 5th on top. Augmented triad: two stacked major 3rds (+4, +4), unsettled with an augmented 5th.
Listen first for major versus minor (the quality of the lower 3rd), then check the outer interval: a perfect 5th means major or minor, a diminished 5th means diminished, an augmented 5th means augmented. Tick one box.
2023 SACE Stage 2-style2 marksTick the appropriate box to indicate which chord is played: E dominant seventh, E minor seventh, E half-diminished seventh, or E augmented seventh.Show worked answer →
Two marks for naming a seventh chord built on E. All share the root E but differ in the triad quality and the type of 7th added.
E dominant 7th (E7): major triad (E G# B) plus a minor 7th (D), bright with a strong pull to resolve. E minor 7th (Em7): minor triad (E G B) plus a minor 7th (D), mellow and stable. E half-diminished 7th (Em7b5): diminished triad (E G Bb) plus a minor 7th (D), tense and used as a pre-dominant ii in minor keys. E augmented 7th (E+7): augmented triad (E G# B#) plus a minor 7th (D), very unstable.
Decide first whether the triad sounds major, minor, diminished, or augmented, then confirm the 7th. The combination identifies the chord. Tick one box.
Practise this
Sources & how we know this
- SACE Music subjects: overview and subject outlines — SACE Board