What are the most common chords, how are they built, and how do cadences make music sound finished or unfinished?
Build the primary triads in a key, name them with Roman numerals, and identify the perfect and imperfect cadences that close or open a phrase
A clear answer to the N(A)-Level Music outcome on chords. Building triads, the three primary chords I, IV and V, naming them with Roman numerals, and hearing the perfect and imperfect cadences that make a phrase sound finished or unfinished.
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What this dot point is asking
SEAB wants you to build the most common chords in a key, name them with Roman numerals, and hear how cadences make a phrase sound finished or unfinished. The big idea is that harmony in simple music runs on a few main chords, and that cadences are like punctuation: they tell the ear where a musical sentence ends and whether it is a full stop or a comma.
The answer
Building a chord: the triad
A triad is a three-note chord built by stacking thirds: a root, the note a third above it, and the note a fifth above the root. For example, on C the triad is C, E, G. A triad is major if the third is a major third above the root (bright) and minor if the third is a minor third (darker).
The three primary chords
In any major key, three chords do most of the work. Naming chords by the scale degree of their root with a Roman numeral (upper case for major):
- Chord I (tonic): built on degree 1, the home chord, stable and restful.
- Chord IV (subdominant): built on degree 4, a chord of preparation.
- Chord V (dominant): built on degree 5, a chord of tension that pulls back to I.
In C major these are I = C, E, G; IV = F, A, C; V = G, B, D. These three primary triads can harmonise most simple tunes.
What a cadence is
A cadence is the chord progression at the end of a phrase, like punctuation in a sentence. The two most important at this level are:
- Perfect cadence (V to I): lands on the home chord and sounds finished, like a full stop.
- Imperfect cadence (ending on V): stops on the dominant and sounds unfinished, like a comma, wanting to go on.
A third type, the plagal cadence (IV to I), is the gentle Amen close heard at the end of hymns.
Why cadences work
The dominant chord V contains the leading note (degree 7), which leans strongly up to the tonic. When V moves to I, that pull is satisfied and the music feels settled. When the phrase stops on V instead, the pull is left hanging, so the ear expects more.
Examples in context
Example 1. A simple hymn. Hymns are built almost entirely from the primary chords I, IV and V, with a clear cadence at the end of each line. Listening for the full-stop perfect cadences and the comma-like imperfect ones is the easiest way to hear cadences at work.
Example 2. A folk or pop song with three chords. Countless folk and pop songs use only three chords, the tonic, subdominant and dominant of their key. Recognising this shows how far the three primary triads can stretch and why they are the foundation of basic harmony.
Try this
Q1. Build the tonic triad in C major and name its three notes. [2 marks]
- Cue. The tonic triad (chord I) in C major stacks thirds on C: C, E and G.
Q2. Name the two chords that make a perfect cadence and say how it sounds. [2 marks]
- Cue. A perfect cadence is chord V to chord I; it lands on the home chord and sounds finished, like a full stop.
Q3. Explain why a phrase that ends on chord V sounds unfinished. [3 marks]
- Cue. Ending on the dominant V leaves the music on a chord of tension, with its leading note still pulling toward the tonic, so the ear expects the phrase to continue, an imperfect cadence.
Exam-style practice questions
Practice questions written in the style of SEAB exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
Original6 marksIn the key of C major: (a) build the tonic triad and name its three notes. (b) Name the chords on degrees 4 and 5 and give their Roman numerals. (c) State which two chords form a perfect cadence.Show worked answer →
(a) The tonic triad is built on degree 1 (C) using the root, the third above and the fifth above: C, E, G. This is chord I.
(b) Degree 4 is F, so chord IV is the F major triad (F, A, C). Degree 5 is G, so chord V is the G major triad (G, B, D).
(c) A perfect cadence is chord V to chord I (in C major, G major to C major).
What markers reward: building the triad correctly in stacked thirds, naming chords IV and V with both the notes and the Roman numerals, and identifying V to I as the perfect cadence. The strongest answers note that these three chords (I, IV, V) are the primary triads that can harmonise most simple tunes.
Original5 marksTwo phrases of a hymn are played. The first phrase ends and sounds unfinished, like a comma; the second ends and sounds complete, like a full stop. (a) Name the cadence likely used at each phrase end. (b) Explain in words why one sounds finished and the other does not. (c) State which chord both cadences share.Show worked answer →
(a) The first phrase most likely ends with an imperfect cadence; the second ends with a perfect cadence.
(b) The perfect cadence moves from the dominant chord V to the tonic chord I, landing on the home chord, so it sounds complete. The imperfect cadence ends on chord V (the dominant), which feels unsettled and wanting to continue, so it sounds like a comma.
(c) Both cadences involve chord V (the dominant); the difference is whether the music then lands on I (perfect) or stops on V (imperfect).
What markers reward: naming the imperfect and perfect cadences correctly, explaining the finished feel as landing on the tonic I after V, and noting that chord V is common to both. A strong answer uses the comma versus full stop image to show understanding.
Related dot points
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