Triads in Major and Minor Keys

Triads in Major and Minor Keys

Chapter 7

Triad Qualities in Major Keys

When identifying triads in a major key, you can refer to each triad with a Roman numeral corresponding to the scale degree it is built off of. Major chords are represented with a capital Roman numeral, minor chords are represented with a lower case Roman numeral, diminished chords are represented with a lower case Roman numeral followed by a ^o, and augmented chords are represented with a capital Roman numeral followed by a +.​

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Major: I II III IV V VI VII

Minor: i ii iii iv v vi vii

Diminished: i^o ii^o iii^o iv^o v^o vi^o vii^o

Augmented: I+ II+ III+ IV+ V+ VI+ VII+

Multiple Choice

Which Roman numeral represents a minor triad?

• VI

• vi

• vi^o

• VI+

Multiple Choice

Which Roman numeral represents a major triad?

• I

• i

• i^o

• I+

Multiple Choice

Which Roman numeral represents an augmented triad?

• iii

• III

• iii^o

• III+

Multiple Choice

Which Roman numeral represents a diminished triad?

• VII

• VII+

• vii

• vii^o

More on Roman Numerals

You can also refer to triads by their scale-degree name. In other words, if the root of a chord is scale degree 5 in the key, you would call it the dominant chord. If the root of a chord is scale degree 1 in the key, you would call it the tonic chord.​

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1 = tonic chord

2 = supertonic chord

3 = mediant chord

4 = subdominant chord

5 = dominant chord

6 =submediant chord

7 = leading tone chord

How to Use Roman Numerals

When writing Roman numerals, you MUST indicate the key to the left. A V chord (dominant chord) means nothing unless you know what key you are in.​

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Every major key will the same chord quality built on each scale degree. This means we can always expect the tonic chord in a major key to be a certain quality.

Example

If we built diatonic triads on the scale degrees in a major key, we end up with I ii iii IV V vi vii^o. Remember, diatonic means we only use notes found in the key.​

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Notice in the D major example, we indicated the key the major key with a capital D to the left of the Roman numerals. That means even if we covered up the notes, we would know that the iii chord was a minor chord built off of the root F# because F# is scale degree 3 in D major.

Fill in the Blanks

What is the Roman numeral for the tonic chord in a major key?

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What is the Roman numeral for the dominant chord in a major key?

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What is the Roman numeral for the submediant chord in a major key?

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What is the Roman numeral for the leading tone chord in a major key?

Augmented Triads

Did you notice which chord quality we did not use in the major key? Augmented triads do not occur diatonically in major keys.

Why Do We Use These?

Roman numerals help you understand the patterns and progressions of the chords. They also help you transpose quickly. For instance, I IV V could be...

D: D G A

A: A D E

B: B E F#

While the notes change depending on the key, the quality of the chords and the relationship between them remains the same.

Triads in Minor Keys

Because minor keys have variations that are used on scale degrees 6 and 7 vs. b6 and b7, we end up with more possibilities.​

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1 = do, tonic

2 = re, supertonic

b3 = me, mediant (same name)

4 = fa, subdominant

5 = sol, dominant

b6 = le, submediant (same name)

6 = la, raised submediant (new name)

b7 = te, subtonic (new name)

7 = ti, leading tone

Roman Numerals in Minor Keys

Minor keys often use the natural minor scale for their chords. This creates the following triads:

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natural minor: i iio III iv v VI VII

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However, the harmonic minor is often used in the harmony, aka the chords/triads (harmonic... harmony... get it?). The harmonic minor changes b7 to 7, giving us a leading tone instead of a subtonic.

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harmonic: i iio III+ iv V VI viio

Harmonic Minor

Did you notice that the harmonic minor produced an augmented triad (III+)? This chord is extremely rare. Typically, a major triad (III) is used instead, just like you'd see in the natural minor. The most likely chords you will see in a minor key are:

i ii^o III iv V VI vii^o

However, v and VII are still used, and occasionally you will see a III+ (but don't hold your breath).

Fill in the Blanks

What is the Roman numeral for the tonic chord in a minor key?

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What is the Roman numeral for the supertonic chord in a minor key?

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What is the Roman numeral for the subtonic chord in a minor key?

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What is the Roman numeral for the dominant chord in a minor key using the raised 7th from the harmonic minor?