Unit 5 · Lesson 10 of 12 — IB MYP: Personal and Cultural Expression · Communication
Chord Tones & Arpeggios
A triad can sound simultaneously as a chord or unfold one pitch at a time as an arpeggio. Arpeggios turn harmony into melodic motion while keeping the chord identity clear.
In this lesson
Learning Targets
Each section below is labeled with the target it teaches. The questions and your Noteflight task practice every target.
Target 1Distinguish a block chord from an arpeggio
Target 2Identify chord tones in I, IV, and V
Target 3Use arpeggios to outline harmony
IB MYP connection
Command terms: IDENTIFY · APPLY
IdentifyApply
Learner Profile · ATL
Knowledgeable · Thinker — Thinking: connect scale and chord knowledge to the melodies and harmonies you build.
Task
Use what you're learning to complete the Noteflight task below, then check your own work before moving on.
Inquiry: How does spreading a chord out into an arpeggio change the same three notes into a melody?
Reflect: What did “Chord Tones & Arpeggios” teach you about your own composing choices?
Key words
Words you will use today
Block chord
All the notes of a chord sounding at the same time.
Arpeggio
The notes of a chord played one after another instead of together, usually moving up or down through the chord.
Chord tone
A note that belongs to the chord (Primary Chords & Melody). In I in G major, every G, B, and D, in any octave, is a chord tone.
Outline
A melody outlines a chord when its notes are that chord’s notes, so a listener can hear the harmony even with no chords playing.
Tonic chord (I) / dominant (V)
The stable chord on degree 1 and the tense chord on degree 5 (Tension & Resolution).
Two ways to sound a chord
Target 1
Block chords and arpeggios
A triad can sound all at once, as a block chord, or one note at a time, as an arpeggio. The chord’s identity is the same either way: the same three letters. What changes is the texture. A block chord gives a single, solid sound; an arpeggio turns the harmony into motion, so the chord becomes something you can hear as a melody.
01
Block chord
G–B–D sounding together: the tonic chord in G major as one sound.
I in G major as a block chord.02
Arpeggio
The same chord unfolded upward, G–B–D, then the root an octave higher. Every note is still a chord tone of I.
I in G major as an arpeggio.03
In real music
Bach’s Prelude in C major is built almost entirely from arpeggios: each measure unfolds one chord, then repeats the pattern. Measure 1 is the C chord spread over two octaves, C–E–G–C–E.
Bach, Prelude in C major, BWV 846, m. 1: all C, E, and G (held notes shown as a single line).
Spelling the primary chords
Target 2
Chord tones of I, IV, and V
To use chord tones, you need to know each chord’s three letters without stopping to count. In G major: I = G–B–D, IV = C–E–G, V = D–F♯–A. A chord tone can appear in any octave and in any order: an arpeggio can start on the 3rd or 5th, skip around, or double a note an octave higher. The test is always the same: is this letter one of the chord’s three?
01
I: G–B–D
Up through the chord to the high root, then back down. Every note is G, B, or D.
G major, I.02
IV: C–E–G
This arpeggio dips below its root to a lower G. That G is still a chord tone of IV.
G major, IV.03
V: D–F♯–A
This one starts on the 5th, A. The F♯ comes from the key signature, and it is the leading tone.
G major, V. Both Fs sound as F♯.
Melody that carries harmony
Target 3
Using arpeggios to outline the harmony
A melody built from an arpeggio outlines the chord: even with no accompaniment, the listener hears which harmony it implies. Composers use this constantly, especially at the start of a piece, when the key needs to be established quickly.
01
Mozart outlines I
The opening of Eine kleine Nachtmusik uses only G, B, and D. Played by strings alone with no separate chords, it still announces G major and its tonic chord in two measures.
Mozart, Eine kleine Nachtmusik, K. 525, opening (first violin). All chord tones of I.02
An anthem outlines I
“The Star-Spangled Banner” opens with a C major arpeggio: G–E–C, then back up E–G–C. You saw in Unit 1 that it moves only by skips and a leap; now you can say why. It is spelling the tonic chord.
“The Star-Spangled Banner” (J. S. Smith), opening, in C: every note is C, E, or G.03
Outlining a progression
Arpeggiate a different chord in each measure and the melody carries a whole progression by itself. This line outlines I–IV–V–I in G major with no accompaniment at all.
Course example, G major: I, IV, V, I, one chord per measure.
Worked analysis
Target 1Target 2Target 3
Arpeggio melody over block chords
Here is the same course example with the chords added as block chords in the bass clef. Now the harmony sounds two ways at once: together, underneath, and one note at a time, in the melody.
Course example, G major: an arpeggio melody over block chords, I–IV–V–I.
Measure
Chord and melody
What the melody does
m. 1
I (G–B–D): G B D G D B
Rises through the tonic chord to high G, then turns back
m. 2
IV (C–E–G): C E G E C G
Outlines IV, dipping below the root to G
m. 3
V (D–F♯–A): A D F♯ D A F♯
Outlines the dominant and ends on the leading tone
m. 4
I (G–B–D): G
The leading tone rises a half step to the tonic, held
Model description: The accompaniment plays I–IV–V–I as block chords, while the melody arpeggiates the same chords one measure at a time, so every melody note is a chord tone. Because the melody spells each chord completely, you could remove the accompaniment and still hear the progression. Measure 3 outlines the dominant and stops on F♯, the leading tone, which resolves up to G on the final I. The arpeggios make the harmony audible in the melody itself.
Notice what the description does: it names the texture of each layer (block chords, arpeggio), checks the melody’s notes against each chord, and points out how the arpeggio over V sets up the resolution to I.
Check your understanding
Try it before you compose
Pick an answer for each question. You will see right away whether you are correct and why.
0 of 6 correct
1Listen, then choose which excerpt you heard.
Target 1
A
B
2Which notes are the chord tones of IV in G major?
Target 2
3Which chord does this opening outline?
Target 2Target 3
4This melody is in G major with no accompaniment. Which chord does m. 2 outline?
Target 2
5Listen only. The melody plays with no chords underneath. What does it outline, and how does it end?
Target 3
6Over V in G major, which melody measure outlines the harmony most clearly?
Target 3Target 2
A
B
Take it to Noteflight
Block chords, arpeggios, and what you hear
Write the tonic and dominant chords of G major both ways, then listen for how the same three notes change character when they unfold one at a time.
Your Noteflight task
In G major, enter G–B–D together as a tonic triad, then use G–B–D successively as an arpeggio. Repeat with D–F♯–A for V and compare what you hear.