• Chord Sequences

    • Chord sequences consist of seven chordal scale degrees that are derived from an original scale. Because all the chords of a chord sequence are from the same scale they sound good together. The chordal scale degrees of a key are arranged by a musicians to create chord progressions in a song. Scale degrees of chord sequences are referred to in Roman Numerals - lowercase for minor (i) uppercase for major (I) and followed with the symbols for augmented (+) or diminished (º). For an entire sequence to be diatonic to one scale/key all the chords must contain only notes that are in the particular scale/key you are dealing with. For example, all the chords of C major are made up of only notes diatonic to C and ascend in the same major scale pattern (WWHWWWH). Not every chord in a major chord sequence is major - the II, III, and VI degrees are always minor, and the VII degree is a flattened major (technically diminished, though rarely used in that form). Playing these degrees of the scale as minor chords allows all the notes played, as mentioned before, to be diatonic to the key of the sequence. For every major chord sequence this sequence of chord qualities is true: major, minor, minor, major, major, minor, diminished (played as a major flat) written as I, ii, iii, IV, V, vi, viiº. Below is a table of all the major chord sequences.

    Diatonic Chord Sequences
    Tonic I II III IV V VI bVII
    C major C Dm Em F G Am Bb
    C# major C# D#m E#m F# G# A#m B
    D major D Em F#m G A Bm C
    Eb major Eb Fm Gm Ab Bb Cm Db
    E major E F#m G#m A B C#m D
    F major F Gm Am Bb C Dm Eb
    Gb major Gb Abm Bbm Cb Db Ebm Fb
    G major G Am Bm C D Em F
    Ab major Ab Bbm Cm Db Eb Fm Gb
    A major A Bm C#m D E F#m G
    Bb major Bb Cm Dm Eb F Gm Ab
    B major B C#m D#m E F# G#m A

    The minor chord sequence formed from the minor scale (WHWWHWW) can also be seen in the table above. The minor chord sequence starts on the VI scale degree of its relative major's chord sequence, the rest of the minor sequence uses the same chords as the major sequence in the same order. For example, Am starts on the VI degree of the C major sequence - Am (I), Bd (II) (in the original diminished form), C (III), Dm (IV), Em (V), F (VI), G (VII). The resulting sequence of chord qualities is minor, diminished, major, minor, minor, major, major written as i, iiº, III, iv, v, VI, VII. The harmonic minor scale can be acheived by using a major V instead of a minor.

    The theory behind chord progressions in music - and the themes we see in them - can be explored in the next section.

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