Chapter 8 | Building a Chord Family
Keep the scale notes. Change where you begin stacking them.
In Lesson 4, we built a major triad from the first, third and fifth notes of its own major scale. Now we’ll build triads on every note of one parent scale.
The important difference: we keep that parent scale’s notes throughout.
Stack alternate scale notes
Write C major beyond one octave so you have enough notes to continue:
C · D · E · F · G · A · B · C · D · E · F · G · A · B
Choose a starting note. Skip the next scale note, take the following one, skip again and take the next.
You now have three notes stacked in thirds:
- Start on C: take C, E and G.
- Start on D: take D, F and A.
- Start on E: take E, G and B.
- Start on F: take F, A and C.
Why is the D chord minor?
D major would contain D, F♯ and A. But our C major parent scale gives us F natural.
D–F is a minor third, so D–F–A is D minor.
We are building chords from the notes already in C major and finding out their qualities. We don’t switch to a new major scale for each starting note.
Keep the parent scale unchanged. Let the notes tell you whether each resulting triad is major, minor or diminished.
Seven roots, one pattern
Continue through all seven notes of C major:
| Degree | Triad notes | Chord | Quality |
|---|---|---|---|
| 1 | C–E–G | C | Major |
| 2 | D–F–A | Dm | Minor |
| 3 | E–G–B | Em | Minor |
| 4 | F–A–C | F | Major |
| 5 | G–B–D | G | Major |
| 6 | A–C–E | Am | Minor |
| 7 | B–D–F | Bdim | Diminished |
Meet the diminished triad
B major would contain B, D♯ and F♯. The triad from C major contains B, D and F. Both the third and fifth are one semitone lower than their major-scale reference.
Diminished triad: 1 + ♭3 + ♭5.
Bdim = B–D–F.
A diminished triad has a minor third and a diminished fifth above its root. It is useful for creating tension.
It is not a diminished seventh chord, which has an additional note.
The pattern travels
Because every major scale has the same step pattern, each one produces this sequence of chord qualities:
Major · minor · minor · major · major · minor · diminished
Apply that pattern to the notes of another major scale and you can find its chord family.
Numbers that travel with you
Roman numerals show a chord’s position and quality within the key.
- Uppercase numerals mean major chords.
- Lowercase numerals mean minor chords.
- A small circle (°) means diminished. We use a lowercase numeral with the circle for a diminished triad.
| Degree | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
|---|---|---|---|---|---|---|---|
| Numeral | I | ii | iii | IV | V | vi | vii° |
| C major | C | Dm | Em | F | G | Am | Bdim |
You may see all-uppercase systems elsewhere. Here, the numeral’s case helps you recognise the chord quality as well as its position.
Try another key
D major contains:
D · E · F♯ · G · A · B · C♯
Apply the same quality pattern without changing those root notes:
| Numeral | I | ii | iii | IV | V | vi | vii° |
|---|---|---|---|---|---|---|---|
| D major | D | Em | F♯m | G | A | Bm | C♯dim |
Play D–G–A–D. Now play G–C–D–G.
Both are I–IV–V–I. The pitches differ, but the relationships follow the same pattern.
A preview of relative minor
The sixth degree of D major is B. Its vi chord is Bm, and its relative minor key is B minor.
D major and B natural minor share the same basic note collection, but they have different tonics.
In a major key, vi identifies the relative minor. The third degree of that natural minor scale leads back to its relative major.
We’ll hear what changes when the tonic changes in Lesson 12. For now, learn to find vi and name the related minor key.
Check your understanding
Build the chords before you reach for a chart. Write your answers before opening the answer section.
1. Build the F major family
Use this parent scale:
F · G · A · B♭ · C · D · E
Starting on each note, stack alternate scale notes to make a triad. Write its three notes, then name the chord.
Your seven starting notes are F, G, A, B♭, C, D and E.
2. Recall the pattern
Write the major-key chord-quality pattern in order.
3. Name the formula
Give the formula for a diminished triad.
4. Read the numerals
What does a lowercase Roman numeral tell you in our notation? What does the small circle mean?
5. Find the relative minor
Which degree gives the relative minor of a major key? Name the relative minor of F major.
6. Explain the chord quality
Why is D–F–A a minor chord, even though we built it from a major scale?
Check your answers
1. The F major chord family
| Root | Triad notes | Chord / numeral |
|---|---|---|
| F | F–A–C | F / I |
| G | G–B♭–D | Gm / ii |
| A | A–C–E | Am / iii |
| B♭ | B♭–D–F | B♭ / IV |
| C | C–E–G | C / V |
| D | D–F–A | Dm / vi |
| E | E–G–B♭ | Edim / vii° |
2. The quality pattern
Major · minor · minor · major · major · minor · diminished.
3. Diminished triad formula
1 + ♭3 + ♭5, measured against the major scale on the chord’s root.
4. Roman numerals
Lowercase means minor. The small circle means diminished. For a diminished triad, we write a lowercase numeral plus the circle.
5. Relative minor
The sixth degree, vi. F major’s relative minor is D minor.
6. Why D–F–A is minor
D–F is a minor third; D–A is a perfect fifth. The parent scale’s major quality does not make every triad in it major.
Play the result
Choose F, B♭ and C, or ask your teacher for manageable shapes. Play:
| F | B♭ | C | F |
Then replace B♭ with Dm:
| F | Dm | C | F |
Listen to the difference. Both progressions use the F major family, but choosing a different chord changes the movement of the music.
What to remember
One parent scale. Seven triads. One repeatable pattern of qualities.
Keep the scale’s notes, stack them in thirds, and identify the intervals above each chord’s root. The chord family follows from those distances.