(Altered) Tension b9
You will never face a minor second written as b2 in a chord name. It will always be seen as (altered) chord tensions that extends a chord that contains a 7th and therefore it is notated as b9.
The b9 should be written in parentheses after the 7th, e.g. G7(b9) or together with other (altered or natural) tensions like e.g. G7(b9,13) or G7(b9,b13). It can also be played, if the chord is written in a generalized form with the extension alt, e.g. G7alt or G7(alt). That means play a G7 chord with altered tensions of your own choice.
In practice the b9 is typically played in dominant 7th chords that resolve from V to I (via a perfect fifth downwards), e.g. G7(b9) → Cmaj7, G7(b9) → Cm7, F7(b9) → Bb, etc.
Theoretically you might name a chord containing the tones C, G and Db a Csusb2. I never came across such a chord name, because it is more likely a a C7(b9) where the 3rd and 7th are just not* played...??? Well, if you want to torture your audience with such a chord: Csusb9 or C7(b9,no3,no7) or C(addb9,no3)...
If you definitely want the player NOT to play certain intervals, you can append the information "no3" or "omit3" respectively "no7" or "omit7" to the chord symbol.
If a chord has a major second but no 3rd, the it's a sus2 chord, e.g. Csus2.
Sus stands for suspended, meaning the 3rd has been suspended and replaced by the major 2nd.
If a chord has a 3rd (minor 3rd or major 3rd) AND a major 2nd, then the major 2nd is called a chord extension and notated as 9. We need to distinguish between two cases:
- 9, if the chord also has a 7th. We can write the 9 in brackets oder separated by a slash behind the 7 or even more commonly instead of the 7, e.g C7(9) respectively C9, Cmaj7(9) respectively Cmaj9, Cm7(9) respectively Cm9, etc.
- add9, if the chord has no 7th at all, e.g Cadd9 or Cm(add9). I'd recommend to put add9 in brackets to avoid confusing sequences of letters like e.g. Cmadd9 or Abadd9.
(Altered) Tension #9
If a chord contains a major 3rd (3) AND a minor 3rd (m3), the minor 3rd is considered to be an augmented 2nd. Otherwise you would have two 3rds in one chord. Since you have a 3rd in the chord, the augmented 2nd is seen as (altered) chord extension and thus written as #9 in the chord symbol.
It is recommended to enclose the #9 in brackets, like e.g. G7(#9). If it's the only tension you might just write G7#9, because it's clearly visible that the # doesn't belong to anything else but the 9.
You can also play a #9 if the chord is written in a generalized form with the extension alt, e.g. G7alt ord G7(alt). That means play a G7 chord with altered tensions of your own choice.
In practice the #9 is typically used with dominant 7th chords, e.g. G7(#)9, E7(#9)
Chords are stacks of (minor and major) thirds. Root, minor 3rd and a perfect 5th (which is the minor 3rd plus a major 3rd) are making a minor chord. Since chords are equipped with a third by default, there is no 3 mentioned in the chord symbol. We just write a m or a minus for having a minor 3rd (e.g. Am or A-).
In more traditional music lowercase letters are often standing for minor chords (e.g. "a" instead of "Am"). Many so called fakebooks or realbooks for jazz and pop use "MI" oder "mi" for minor. If at all I'd only recommend this for handwritten chord symbols, writing the "MI" or "mi" a little bit smaller than the root and with a little space after the root.
Chords are stacks of (minor and major) thirds. Root, major 3rd and a perfect 5th (which is the major 3rd plus a minor 3rd) are making a major chord. The major 3rd is not mentioned at all in the chord symbol. The chord symbol for a major chord is the root as capital letter, e.g. C, F, Bb, Eb,.. that's it.
If a chord has no 3rd, but a perfect 4th, then it is a sus chord. Sus means that the 3rd has been suspended and you're playing the 4th instead.
In the chord symbol you can write sus4 or just sus, e.g. Csus4 or Csus. Never just write a 4 without the prefix "sus".
Quite rarely, but nevertheless every now and then, you might stumble across an add4 chord. Since the 4th is a chord extension in this case, the chord should correctly be named add11 chord → see 11.
If a chord has a 3rd AND a 4th (in this case mostly a minor 3rd, because 11 typically occurs in minor chords), then the 4th is a chord extension and thus notated as 11 in the chord symbol. Like with the 9, we need to distinguish between two cases:
- 11, if the chord contains a 7th: we can write the 11 (usually in brackets) after the 7 or simply (and most common) instead of the 7, e.g. Cm7(11) respectively Cm11.
- add11, if the chord doesn't have a 7th: e.g. Cm(add11). I'd recommend to put add11 in brackets to avoid confusing sequences of letters like e.g. Cmadd11.
Usually the 11 just appears in minor 7th chords. Exception: when you play certain voicings (e.g. a B major as barre chord on 2nd fret [ B F# B D# ] with the high open e string = add11) a major chord with add11 can sound interesting. The chord then should be played arpeggiated (more or less slowly picked string by string) to get an effect similar to play sus4 and major alternately.
Add11 on the other hand is also really rare in minor chords. In most cases a m(add11) can be seen as a m11, in which the 7 is just omitted (but could also be played).
Before you write a chord symbol you should always ask yourself whether you are analyzing someones playing - "ok, that guy is playing a m11 without 7, so it's a m(add11)" - or you a writing a music sheet for someone else to easily read and play that song (then in 99% of the cases it's m11). See also lesson about sus and add chords.
The diminished fifth (b5) normally comes along with a minor third (m3), forming a diminished chord or a half diminished chord (see table below).
Sus4(b5) is imaginable and written correctly, but you may hardly ever stumble across such a chord (try to play it and you'll know why).
In major chords you'd rather write a #11 than a b5. Every chord has one or more related scales. A b5 in the chords name would implicate that the scale must contain a perfect 4th, but then you'd end up having a scale with 3three halfsteps in a row [3 11 b5]. It is much more likely that the scale contains a perfect 5th or augmented 5th. Consequently writing a #11 is more appropriate in major chords. Nevertheless chord names like e.g. G7(b5) appear quite frequently and we have to accept them.
(Altered) Tension #11
The augmented fourth is also called a tritone. It only occurs as #11 in chord symbols, never as #4.
It appears in dominant 7th chords like e.g. G7(#11) or Db7(#11) as well as in major 7th chords like e.g. Fmaj7(#11). If you stack thirds starting on the fourth scale degree of a major scale you'll end up with a maj7 chord having a #11 as a natural extension tone. In the C major scale this would be Fmaj7 with B being the #11 to it.
In practice you'll play the #11 by replacing the 5th and going down one fret instead on the guitar. However, it's still a #11 and not a b5, because that would implicate that the related scale has a perfect 4th (11) and a diminished 5th (b5)... (see description for b5).
Root - major 3rd - perfect 5th form a major chord, root - minor 3rd (m3) - perfect 5th form a minor chord.
Every chord contains a perfect 5th as long as there is nothing stated to the contrary in the chord symbol like b5 (dim) or #5 (+,aug). The perfect 5th can be omitted, especially to free a string or a finger for chord extensions like 11, #11, b13 or 13.
If you see a perfect 5th written in the chord symbol, e.g. G5 or C5, the this is a so called power chord (typical for rock guitar riffs). This "chord" only contains root and perfect 5th.
The augmented fifth (#5) normally goes along with a major third (3). That is what we call an augmented chord. If there is no 7th in the augmented chord, it's written with a plus or the abbreviation aug, like e.g. C+ or Caug, sometimes also C+5 or C5+, rarely C(#5). In the last case you have to enclose the #5 in brackets, otherwise it might be understood as a C# power chord.
If the chord is equipped with a 7th or maj7, you should prefer to use + or #5 instead of aug, e.g. C+7, C7(#5), Cmaj7(#5). Sometimes you'll find the use of + confusing and you'll stumble across wrong chord symbols: C+7 is sometimes written instead of C7+, which is an alternative (but unpreferable) writing for Cmaj7 ..and vice versa C7+ may incorrectly be written for C7(#5). Conclusion: better use #5 when a 7th is part of the game.
The minor sixth (b6) is very uncommon in chord names. If the minor sixth occurs in a chord, it more likely has the function of an (altered) chord extension b13 or an augmented fifth #5.
In the case it's really a b6, then it probably comes along with a minor chord, e.g. Cm(b6). But that one on the other hand is often seen as slash chord with the b6 being the root. So Cm(b6) would be written as Ab/C respectively Abmaj7/C.
(Altered) Tension b13
The minor 6th is notated as b13, if the chord contains a 7th. It belongs to the group of altered chord extensions (so called "altered tensions").
The b13 should be written in brackets like e.g. G7(b13) or along with other tensions, e.g. G7(b9,b13). You can also play a b13, when the chord symbol says "alt", e.g. G7alt or G7(alt). That means play a G7 with altered tensions of your own choice.
You'll find the b13 especially in dominant 7th chords that resolve by a descending fifth (from V to I). Examples: G7(b13) → Cmaj7, G7(b13) → Cm7, F7(b9) → Bb, etc.
The major 6th is written as a 6 in the chord symbol, when there is no 7th (7 or maj7) and thus it represents the fourth tone of the basic chord.
If the chord contains a 7 or maj7, then the major 6th functions as chord extension 13, e.g. G7(13) respectively G13 or Cmaj7(13) respectively Cmaj13.
Very frequently the chord extension 9 is added to a 6th chord ("six-nine chord"). This type of chord is often written with a slash, like e.g.C6/9. Here we prefer to write 6(9), e.g. C6(9).
The major 6th is notated as diminished 7th (dim7 or °7), if it forms a diminished chord together with the root - minor 3rd (m3) - diminished 5th (b5), e.g Cdim7 respectively C°7. In practice the 7th is often not written but in most cases Cdim or C° means the whole four tone chord.
If you name each tone of a diminished chord, the diminished 7th of a Cdim7 is strictly speaking a Bbb and not an A. In practice no one should blame you for calling it an A and even write it on a music sheet like that.
If a chord contains a 7 or maj7, the major sixth functions as chord extension and appears as 13 in the chord name, e.g. G7(13) respectively G13 or Cmaj7(13) respectively Cmaj13.
In comparison with the other intervals that classify into minor and major (2nd, 3rd and 6th) and their minor variants are written with b (or -/m in the case of the 3rd), the minor 7th is just written as plain 7, while its major counterpart is specially marked as maj7 (MA7, j7, etc...) in the chord symbol. This is remarkable,since the natural 7th of the major scale is a maj7.
The minor 7th is the natural 7th in minor 7th chords, e.g. Dm7 or Am7. Together with a major chord the minor 7th forms a dominant 7th chord, like a G7.
The major 7th (maj7) is the natural 7th tone of the major scale. It's the interval with the most different writings. Here we prefer maj7, but you'll often find Cj7 CMA7 CΔ7 or even C7+ (which causes stomach ache for the author, since there a so many better alternatives and the + should be reserved for the #5)
Maj7 chords are located on the first and fourth scale degree of each major scale, like Cmaj7 and Fmaj7 in a song played in C major. But you'll also find minor chords with a maj7 from time to time. Then, for better reading, you should enclose the maj7 in brackets, e.g. Cm(maj7) or C-(Δ7). No brackets are needed when elevated: Cmmaj7 respectively C-Δ7.