[THEORY] 7th chords and scale degrees

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This topic contains 2 replies, has 2 voices, and was last updated by Andrei Moraru Andrei Moraru 7 months ago.

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  • #181276
    Andrei Moraru
    Andrei Moraru
    Participant

    Hello one and all and welcome to our latest installment in the realm of music theory. This time around, we will be talking about seventh chords (and scale degrees).

    When it comes to diatonic scale (major/minor scales), each and every note of the scale has a degree associated to it. While their names are not relevant to this post, we usually use roman numerals to name each degree. Asd we all know, diatonic scales have 7 different notes in them, with the 8th one being a repeat of the first one (the tonic) an octave higher. As a result, each note while have a roman numeral degree associated to it that corresponds to its position in the scale.

    For the C major scale, C will have the I degree (which is also known as the tonic, the root note of the chord), D will have the II degree and so on. Now that we got that out of the way, let’s move on.

    Seventh chords are obtained by adding a variation of the seventh note/degree of the major scale on top of one of the four important triads. We have a total of 5 common 7th chords that we can obtain:

    • major 7th chords, which are usually notated as maj7 – these chords consist of a major triad on top of which we add a major seventh; thus, based on the degrees of the major scale, the formula for maj7 chords is 1 3 5 7; an example of a maj7 chord is Cmaj7, which consists of the C, E, G and B notes (the 1st, 3rd, 5th and 7th notes/degrees of the C major scale)
    • dominant 7th chords, which are usually notated as 7 – these chords consist of a major triad on top of which we add a minor seventh; thus, based on the degrees of the major scale, the formula for 7 chords is 1 3 5 b7; an example of a 7 chord is C7, which consists of the C, E, G and Bb notes (the 1st, 3rd, 5th and flatted 7th notes/degrees of the C major scale)
    • minor 7th chords, which are usually notated as m7 – these chords consist of a minor triad on top of which we add a minor seventh; thus, based on the degrees of the major scale, the formula for 7 chords is 1 b3 5 b7; an example of a m7 chord is Cm7, which consists of the C, Eb, G and Bb notes (the 1st, flatted 3rd, 5th and flatted 7th notes/degrees of the C major scale)
    • minor 7th flat 5 chords, which are usually notated as m7(b5) – these chords consist of a diminished triad on top of which we add a minor seventh; thus, based on the degrees of the major scale, the formula for 7 chords is 1 b3 5 b7; an example of a m7(b5) chord is Cm7(b5), which consists of the C, Eb, Gb and Bb notes (the 1st, flatted 3rd, flatted 5th and flatted 7th notes/degrees of the C major scale); they are also known as half-diminished chords
    • diminished 7th, which are usually notated as dim7 – these chords consist of a diminished triad on top of which we add a diminished seventh; thus, based on the degrees of the major scale, the formula for 7 chords is 1 b3 5 bb7 (that is in fact a double flatted seventh note, which enharmonically is the same as a major sixth); an example of a dim7 chord is Cdim7, which consists of the C, Eb, Gb and Bbb (or A, if you will) notes (the 1st, flatted 3rd, flatted 5th and double flatted 7th notes/degrees of the C major scale)

    Diminished 7th chords are the odd ones out, since they don’t really occur in the major or natural minor scales. However, you can play them to add color to your progressions, though it requires a more chromatic approach to your scales. They can be played in your progressions by having the root note be the half-step between two notes from a diatonic scale which are separated by a whole step.

    And since that was quite a mouth full, think of it like this. If your song is written in C major, then dim7 chords can be played for an added suspense effect on D# (which is located between C and D), F# (located between F and G), G# (located between G and A) or A# (located between A and B). Try playing around with them to see if you like them. I’ve actually written a more detailed post about diminished 7th chords here, where I also show you some forms for Cdim7.

    So, where do these chords occur in a scale? Well, for major scales it’s like this:

    • the I and IV chords (the ones formed on the 1st and 4th degrees) are maj7 chords
    • the II, III and VI chords (the ones formed on the 2nd, 3rd and and 6th degrees) are m7 chords
    • the V chord (the one formed on the 5th degree) is a 7 chord and as you’ll notice, it has a very strong tendency to want to be resolved with the tonic chord (the I chord, which is a major chord)
    • the VII chord (the one formed on the 7th degree) is a m7(b5) chord

    For a minor scale, the chord types are the same, only you need to consider the VI degree of the major scale as the tonic degree (I).

    Sound wise, maj7 chords are somehwat peacefoul sounding if you will (kind of like a musical sigh), 7 chords are very tense and usually feel the need to be resolved somehow. m7 chords to me feel…undecided, very useful if you want to induce a state of confusion if you will, while m7(b5) and especially dim7 chords are very useful to induce a state of suspense and eerie tension.

    That about covers it for this post. If you have any questions, feel free to ask them down below.

    Previous posts:

    Notes, pitches, semitones and octaves
    Accidentals and enharmonic-notes
    Musical Intervals
    Triads
    Suspended Chords

    Want even more musical theory aspects? Then visit my website here

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    #181277
    Ids Schiere
    Ids Schiere
    Participant

    Nice!

    The VII chord is usually referred to as half diminished but that is kind of whatever you like to call it. Another thing is that Roman numerals generally refer to Harmony like ii-V-I etc. These Roman numerals are determined by the scale degree as you say!

    Also, to make everything a bit easier lower case Roman numerals refer to minor (ii, III etc.) And capital Roman numerals are major(I, IV etc.). Also for a minor scale the chords would be i II° III vi v VI VII. Where ° stands for half-diminished. As you can see the v chord is not romantic any more. In this case the VII would be the dominant one. The thing to look for first when you want to determine the key of a song is whether there is a dominant chord in there. When there is you can figure out which major scale(we don’t care about the tonic so much for now) to use over that. From there and the fact that there is a tonic(usually the first chord of a chord progression) you can readily determine the key signature of the song (modes, major, minor etc.)

    Sorry for all the extra information but an application of the information seems nice as well.

    #181280
    Andrei Moraru
    Andrei Moraru
    Participant

    Nice additions.

    There’s also a more subtle reason as to why some roman numerals are lower case and some uppercase. The reason has something to do with the type of each chord, which is once again based on each note degree. Lately I’ve seen that degrees are far more important than I originally gave them credit for.

    We’re going to go into the science behind chord progressions in a future lesson, and it will all come into place.

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