Learn a quick and easy approach to building chords in any major or minor key with roman numerals.
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We can create a full set of triads from any Major Key by using each note of the key as the root of a new chord. For example, if we wanted to build a triad with the root note D from in the key of C Major, we would select the notes D, F, and A as our root, 3rd, & 5th.
C D E F G A B
Notice that D & A are still separated by a Perfect 5th interval, but D & F are separated by a Minor 3rd interval. So in this case, we are building a D Minor triad. Let’s take this a step further and build out all 7 triads in the key of C Major:
This approach also extends to Seventh Chords. Again, let’s use the key of C Major as an example:
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Even though we’ve just been using the key of C Major for all our examples so far, you can build chords in any other major key by following the same patterns and rules.
An easy way of applying what you’ve learned to other major keys is to memorize the patterns of chords as Roman Numerals to express their tonality.
The chords are then numbered starting from the tonic. So, in the key of C Major, our C Major Triad would be the ‘I’ chord. And, the D Minor triad would be the ‘ii’ chord.
For every Major Key we can use this pattern to build its respective triads:
Here’s how the triads in the key of C Major would be expressed as Roman Numerals:
If we followed this same Roman Numeral pattern for another major key, we can very quickly create its respective triads. For another example, let’s use the key of G Major:
G A B C D E F♯
We certainly could build all the chords in the key of G Major by analyzing each interval. However, a much faster way is to apply our Roman Numeral pattern:
When we apply this Roman Numeral pattern to Seventh Chords in a Major Key, we need to get a bit more specific with our naming because of the various tonalities that seventh chords provide.
The upper-case (major tonality) and lower-case (minor tonality) rules still apply, however we must define our major seventh chords with a ‘maj7’ suffix and our minor seventh chords with a ‘m7’ suffix.
This is mainly because of the Dominant chord which only includes a ‘7’ suffix and not a ‘maj’ or ‘m’ since it is technically neither tonality (it has a ‘dominant’ tonality).
You’ll also notice that the Minor Seventh Flat Five chord gets a unique spelling as well to show that it is a minor 7th chord with a flat 5 (♭5) interval.
Again, you can still apply this pattern to any Major Key to create its seventh chords.
For example, in C Major we get: Cmaj7 – Dm7 – Em7 – Fmaj7 – G7 – Am7 – Bm7♭5
Or, in the key of G Major: Gmaj7 – Am7 – Bm7 – Cmaj7 – D7 – Em7 – F♯m7♭5
Remember that the Roman Numeral pattern for chords in a Major Key is: I – ii – iii – IV – V – vi – viio. In Minor Keys, the pattern is:
Using the key of C Minor (C D E♭ F G A♭ B♭) as an example, this pattern would create these triads:
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For Seventh Chords, the Roman Numeral pattern is also slightly different in Minor Keys.
Remember that the pattern for Seventh chords in a Major Key is: Imaj7 – iim7 – iiim7 – IVmaj7 – V7 – vim7 – viim7(♭5)
In Minor Keys, this pattern is:
Using C Minor (C D E♭ F G A♭ B♭) as the example key, we would get these chords:
Cm7 – Dm7♭5 – E♭maj7 – Fm7 – Gm7 – A♭maj7 – B♭7