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I am new to the world of music theory and have some basic knowledge of the different modes of the major scale.

As per my knowledge, every scale has a tonic chord which is essentially the one all other chords seem to revolve around. The tonic chord needs no furthur resolution, blends in extremely well within the entire piece and when the listener listens to this chord they feel 'at home'. All other chords lack this central vibe and are unresolved.

Now, when I read about the Locrian mode, for example, I read that its tonic chord is a diminished chord. Well, that is quite ambiguous, since that is quite unstable in itself. And if that is the case, the diminished chords and other chords should reverse roles when in a Locrian piece right? What I mean is, when a piece is in the Locrian mode, and suppose I play a major (or minor) chord, will one get a feeling of instability? Will the piece then have a tendency to resolve to a diminished chord?

Also, talking about tonic chords, if there exist scales with diminished chords as the tonic chord, there must be scales with suspended chords, augmented chords, and chords with more than 3 notes as the tonic chord, right? Can someone please give examples of such scales and do the same rules apply to them too?

I would really appreciate it if anyone can throw some light on these things since the idea of it is very unclear to me.

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About the "tonic"

Not every scale has a tonic chord.

Tonic is primarily a concept in major/minor Tonality and does not apply (the same way) in modality or to non major/minor-Tonal music. When other kinds of musical structures are involved (the Locrian mode, for example), one more generally speaks of a pitch center, which is a more general term that can apply to most music that is not atonal.

"Tonic" vs. I-chord

In the major/minor Tonal system, the tonic chord and the I (or i) chord — that is, the chord with the first scale degree as its root — are synonymous. This is not true in other systems. The I chord does not necessarily serve a "tonic" function: i.e., is not a point of resolution, as is clearly the case in Locrian. In Locrian, specifically, the first scale degree can function as the pitch center, and that individual pitch might function like a tonic, but there is no "tonic chord" in the sense of a "place of rest".

Major/minor chords in Locrian

When using the Locrian mode, one would tend to avoid prominent major or minor chords. It is generally in the nature of these chords to sound stable, and to draw the ear, and so they would tend to undermine the unique sound of Locrian and shift the music toward sound like major or minor.

Chords within scales

A definition of "chord"

For this to have meaning, we need to adopt a mildly restrictive definition of chord. For our purposes, let's say a chord comprises three pitches separated, each separated by one scale pitch.

So, for example, in C major, C E G is a chord, but C D G is not, because there's no scale pitch between C and D. C F G would also not be an allowed chord, because there is more than one pitch between C and F.

Without this rule, we could construct most any chord from most any scale.

Chords generated by different types of scales

  • Suspended chords: technically, these cannot occur. A suspension is a pitch held over from a previous harmony and so is not properly part of the chord with which it occurs. "Sus" chords are a shorthand for certain non-thirds-based chords. Allowing that a chord is "every other note" in a scale, then the C minor blues scale (for example) has a I chord of C F G, which is typically labeled a Csus4.

  • Augmented chords: The whole-tone scale contains only augmented chords (again, assuming the usual every-other-note pattern.

  • Four-note chords: A chord, by most definitions, only requires three notes. One can (almost) always add a fourth note. But any scale with a four-note chord trivially also contains a three-note chord (by removing the fourth note).

  • Diminished chords: The diminished scales (octatonic scales) contain diminished chords.

Major and minor scales, within the Tonal system, follow the rules being asked about. Other scales follow their own rules — or the rules imposed on them by the composer.


As an aside, I know of one piece in which a major chord takes on (or can take on) a dissonant quality: "A Riveder le Stelle", by Ingvar Lidholm. Almost the entire piece consists of tone clusters, but there is a point at which a C Major chord suddenly emerges. The resonance of it, especially live, can be quite shocking if you don't know (when) it's coming.

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    The (minor) blues scale has a tonic chord that is a sus4 chord according to your "Allowing that a chord is 'every other note' in a scale" rule. Maybe not as contrived as you think? – Dekkadeci Apr 30 at 12:24
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    @Dekkadeci Good call! Do you mind if I include that in my answer? – Aaron Apr 30 at 14:10
  • Major and minor keys can be pretty well defined by a three-note 'tonic' chord. Maybe even a two-note one. But introduce the possibility of other modes, we might need a four-note tonic chord. Otherwise how is a Mixolydian tonic to be distinguished from a major? A Dorian from a minor? – Laurence Payne Apr 30 at 15:35
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    @LaurencePayne, I thought the typical way to say something was a mixolydian tonic was by chord relationships, like G mixo using G, F, dm or just a strong F in mostly G major... well, along with phrasing to highlight G. – Michael Curtis Apr 30 at 17:11
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    I don't think the tonic chord necessarily needs to be uniquely representative of the mode it's in... I agree with Michael Curtis, @LaurencePayne, although including more notes in the tonic chord for stylistic reasons is certainly fine. – user45266 Apr 30 at 17:20
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What do you mean by the tonic chord feels as 'home'?

If it doesn't feel like home, you shouldn't call it a tonic. If it doesn't feel like a center, don't give it the number 1. If you TRIED to make it sound like home, but it did not sound like home, then you FAILED. As simple as that. Maybe you tried to do something that's nearly impossible to begin with, and requires extremely high skills. You can say "Locrian", but you can also say "30 feet jump". Easy to say, not so easy to do.

As per my knowledge, every scale has a tonic chord which is essentially the one all other chords seem to revolve around. The tonic chord needs no furthur resolution, blends in extremely well within the entire piece and when the listener listens to this chord they feel 'at home'. All other chords lack this central vibe and are unresolved.

It's not about which scale and which notes you use, it's how you use them. I highlighted the part that you got wrong. Let's fix it:

A piece or a passage of music CAN HAVE a tonic chord, which is essentially the one all other chords seem to revolve around. The tonic chord needs no further resolution, blends in extremely well within the entire piece and when the listener listens to this chord they feel 'at home'. All other chords lack this central vibe and are unresolved.

Whether a chord is a central chord that everything revolves around, depends on what happens. Listen to the notes. Does chord X feel like being the center? If not, then it's not a tonic! Music CAN have a tonic, IF the composer or improviser is skillful and able to make something sound like a tonic.

If you play the white keys of the piano randomly, the keys being white does not guarantee anything about which modal feeling, if any, you create. If you play totally randomly, then it will be a chaos and none of the notes or chords will be a center. But if there's some kind of order and logic in what you play, then one of the notes might feel like a center. If you can play only white keys so that B feels like the center note and B diminished feels like the center chord, then congratulations, you managed to create a Locrian feel. Be careful with what notes and chords you play, you can break the modal feeling easily.

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You're correct about the Locrian mode. It's rarely used, because 'home' is supposed to be a diminished harmony. Which in itself is unstable. So it's somewhat of an oxymoron. In Western music, it's well established that simple major or minor harmonies (chords) are way more stable than any other. Could that be why the vast majority of pieces are deemed to be in major or minir keys? And even the modes present themselves thus: Dorian = minor, Mixolydian = major, etc.

Scales and modes are man-made things, as we love to pigeon-hole everything! And it just happens that some contain weird chords. That's the nature of ordering things. Doesn't necessarily mean they're useful, just that they exist. The make-up of a diminished chord (as in Locrian) is that it contains what we consider dissonance, which in itself we feel needs to be resolved. Just as when we hear G7 we feel it needs to be resolved to C (o.k. not talking Blues here!), and part of that G7 has BDF contained within it. So in reality, there's no sensible way Locrian can be perceived as 'home', as it is, by definition, unstable. Music has been composed using it, but a lot of the time, its purpose is to use its instability, leaving listeners on the edge of their seats.

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    Locrian is a nasty unstable place, but if you live there long enough, you'll accept it's your home. ;) It feels bad, but you have to go back there because the composer convinced you that it's your home. – piiperi Reinstate Monica Apr 30 at 8:23
  • @piiperiReinstateMonica - sounds just as bad as Turmoil - couldn't get along with being there either... – Tim Apr 30 at 13:30
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Your Tonic chord is simply the core triad, either major or minor that a piece of music is based on. It has nothing to do with "white keys, or black keys" (Sharps or flats). It it the resolution of a perfect 5th in which the third tone of the fifth is the 7th of the base tonic. A simple example: the take a song in the key of C major. That is comprised of C-E-G notes. The fifth note is the G. A major cord build on G is G-B-D. If you have been playing and establishing C as your basis and the play a G chord, your ear and instinct will almost compel you to return to the C chord as the resolution or "Tonic".

Why does this happen? In the example above when we build out the G chord it is a B natural in it. The B is just off enough from C, the human ear feels it to be out of place given that tonality has been set to C for a while in the song. It feel resolved when the next note we hear after that B is the C and for the G to also "resolve" back to C. This a V-I resolution and all keys have them. If the G chord has a flatted 7th tone (F natural) you ear and brain will feel compelled to shift that F to the E and the B to C when resolving to the core tonality that was set. We are hard wired to hear tones resolve this way across all cultures with tonal music. The combination of the B natural and the F Natural (Tri-tone) on its own feels odd to the human ear so you will fell at "Home" once the C chord is played immediately after.

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  • This does a good job answering the title of the question, but it does seem to be mostly information acknowledged in the premise of the question. The question asks about how all of this would work outside of the normal major and minor keys. – user45266 Apr 30 at 17:37
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Your understanding of the tonic chord seems just fine.

Your real question is about locrian mode an whether a diminished chord can be a tonic.

I think you should make a distinction between what are musical conventions and some notion of absolute, objective musical qualities.

There is a very long traditional and some acoustical support of the sense of stability in root position major/minor triads. The perfect fifth is what really gives the sense of stability to these chords and therefore the lack of stability in diminished or augmented triads. Another way to think of the "instability" is augmented triads and (fully diminished seventh) diminished chords do not have one single root position inversion. That particular aspect of augmented/diminished chords is often called symmetry, it gives them a certain ambiguous quality, and that ambiguity could be thought of as the "instability."

Another very old tradition is starting and ending a work on the same chord, the tonic chord. There isn't any acoustical rationale for this, but you can make various comparisons to other arts: an architectural arch, the hero returning home in narrative plot, etc.

Neither of those two traditions is a physical law of the universe. As much as people want to invoke acoustics and the overtone series as a rationale for why root position (major only) chords would be perceived as stable these traditions are cultural choices. Being conventions a musician (that an artist not a scientist) can conform to the conventions or buck them intentionally however they see fit.

I think a nice composition to use as an example is Chopin's Mazurka, Op. 17 No. 4, in A minor. Neither the start nor ending use an A minor chord, nor even a root position major/minor chord. The first clear confirmation of A minor isn't until around the 20th measure, and just before the final phrase there is a clear A minor statement. Incidentally, the very first chord is in ascending order A B F, which you could say is a half diminished chord in fourth inversion, that would superficially be a tonic chord for B locrian. Sonically, you can hear the diminished quality of the chord, but I don't really think it's a locrian tonic, I'm just pointing out the coincidence.

We can play around with metaphors and say the ambiguous opening/ending phrases are introduction/coda representing some emotional or nostalgic turning away while the A minor statements are affirmations, some kind of "home." You could turn it around, the ambiguous opening/closing is some kind of tragic "home" and A minor, and the whole middle section, is some escape fantasy, etc. etc. You can go on and say anything you like about it metaphorically. In technical musical terms Chopin started and ended with an ambiguous phrase using inverted chords of the sixth and placed statements around a tonic A minor internally using the harmonic conventions of tonic/dominant harmony. Nowhere in the music did anyone or anything "go home."

What do you mean by the tonic chord feels as 'home'?

If you don't know music theory terms, explaining tonic with a technical explanation about leading tone, perfect fifth, root position, etc. won't make sense. But, a metaphor that fits a lot of music listening experience will. We could play something simple like Handel's famous sarabande in D minor, point out the starting on a D minor chord, the movement to other chords, and then final return to D minor, have all agree this feels like the music is coming to a conclusion, metaphorically call in returning to "home", and then say that "home" feeling is what make the D minor chord the tonic. The technical fact that those "home" tonic D minor chords are all directly connected to dominant chords is skipped... unless the person is starting to learn music theory. In that case the tonic/dominant relationship is exactly what you point out and explain is actually the way the tonic is defined in music.

Can locrian mode, or a diminished chord be a tonic? Well, by long established historic conventions: no. It would literally be reserving the harmonic roles. A diminished chord normally acts as a dominant or the iio in minor is a subdominant.

If we broaden the meaning of tonic to just mean some "main", "central", "focus", etc. tone or chord - sort of the "home" idea - but rather than being defined harmonically with tonic/dominant chords, it will probably be achieved rhythmically, you could have a so-called locrian tonic. Adam Neely has a good video showing several musicians playing in locrian mode. To the extent that the stuff is in locrian mode we have a locrian center, a tonic.

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You have described perfectly why the Locrian Mode (as a tonic of an entire piece at least) exists almost exclusively in textbooks and contrived exercises. You understand the feeling of 'home', and recognise that a diminished triad doesn't do it very well!

AS to tonic chords:

If major and minor are the only choices of mode, they can be defined by a three-note 'tonic' chord. Maybe even a two-note one. But introduce the possibility of other modes, we start need a four-note tonic chord. Otherwise how is a Mixolydian tonic to be distinguished from a major one? A Dorian one from a minor one? And when we enter the forest of Synthetic modes, ones that aren't derived from the 'white note' scale, even more complex tonic chords are needed. Perhaps the whole scale!

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Take any Baby song, children song, folksong, Spiritual and you will recognize that the song is ending on the root tone and root chord, the tonic.

Ex.:

doremifa sososo_ sofamire dododo_

do mi so - so fa mi re do

latidore mimimi- rerere- mimimi- latidore mimimi- miredoti la—-

Mozart’s first composition ended all: lasofa mi re do.

other clauses in common practice are: solati do or doreti do.

Also church mode tunes are ending stepwise ascending or descending, so it‘s like the melody is landing on the ground, like „coming home“.

(Forget the locrian! This mode is so rarely, and its root tone is normally a leading or passing tone of other modes. Our ear will miss the home feeling here.

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