This page presents a summary of the definition of chord names. This aspect of music theory is useful in Mozart when constructing guitar chords.
Rhythm guitarists are often given a written part simply consisting of the names of the chords to be played - for example:
| C / / / | C / / / | C / / / | C7 / / / | F7 / / / | F7 / / / |...
Such notation is also common on big band parts (for all instruments) where the instrumentalist is expected to improvise a solo fitting with the harmonies of the piece.
Here we give an introduction to defining the meanings of these names. For all but the simplest of chords there is no unique notation, and we shall give some frequently found alternatives. The chords are defined in terms of the intervals between the notes which they contain - see intervals.
|C||C E G|
|Em||E G B|
Examples of the various chord types are given in terms of the chord name shown in bold and its component notes shown in normal text as here on the right.
We construct the names of chords built on a given "root" note. However the "root" does not have to be played as the lowest (bass) note of the chord. For example the notes (CEG) can be played together in any ordering from top to bottom in the chord, that is to say in different "inversions". The naming system discussed here is completely independent of what inversion one is considering (although there are other, older notations which emphasise which inversion is to be played).
[When a rhythm guitarist sees the chord G, for example, he is expected to use his judgement to choose from a number
of ways in which to play it. The considerations include both the inversion which may sound best and the position
on the fingerboard of the available options.]
|C||C E G|
|E||E G B|
A major triad is built from a given root, and the major third and the perfect 5th above the root. The chord thus formed simply takes its name from the root note.
|Cm||C E G|
|Em||E G B|
A minor triad is built from a given root, and the minor third and the perfect 5th above the root. The chord thus formed simply takes its name form the root note followed by 'm' to indicate "minor".
Alternatives: in (for example) big band charts the m is sometimes replaced by - or by mi.
|C7||C E G B|
|Em7||E G B D|
Seventh chords are formed by adding a minor 7th above the root to a major or a minor triad.
[These chords are often called "dominant 7ths". The reason for this is illustrated by the fact that the C7 chord does not
contain notes all from the scale of C major, but it does contain notes which are all from the scale of Fmajor. In fact this chord occurs very
commonly, in a wide variety of musical styles, in the key of F major, in which it is the 7th chord built on the dominant, ie the 5th degree of the
scale, of F.]
|C9||C E G B D|
|C11||C E G B D F|
|C13||C E G B D F A|
|Em9||E G B D F|
|Em11||E G B D F A|
|Em13||E G B D F A C|
Ninth chords are built by adding a major 9th from the root to a seventh chord. Eleventh chords are made by adding a perfect 11th from the root on top of that, and thirteenth chords are made by adding a major thirteenth on top of that.
1. the 11th is often omitted from a 13th chord.
2. seventh, ninth, eleventh, and thirteenth chords are all built by stacking extra thirds on top of the original triad.
They all contain a minor seventh. If we think of C7, C9, C11, C13 built on the dominant of the key of F major,
we see that C13 contains all the notes of the scale of F major, and this is usually, therefore, as far as this process is taken.
|C6||C E G A|
|Em6||E G B C|
Sixth chords are formed by adding a major 6th to a triad.
C6 and Am7 contain exactly the same notes, but nevertheless both notations are current, and in fact may imply a
|Cmaj7||C E G B|
|Emaj7||E G B D|
Major seventh chords are formed by adding a major 7th to a triad.
Note that these have a completely different character from (dominant) seventh chords. There are a number of different notations which are used for these including
Cmaj7, CΔ7, or simply CΔ
|CmΔ7||C E G B|
Major sevenths are generally only very rarely added to minor triads (though there are styles of music in which they appear).
|C°||C E G|
|E°||E G B|
Diminished triads contain a minor 3rd and a diminished 5th above the root.
The symbol ° shown above is very common for diminished chords but they are also very commonly indicated with "dim". Thus alternatives are
|C°7||C E G B|
|E°7||E G B D|
A diminished seventh chord adds a diminished seventh over the root of a diminished triad.
1. The symbol ° may, as above, be replaced by "dim".
2. These chords are probably encountered more often than the diminished triad, and so the "7" is sometimes omitted, effectively leaving it to the discretion of the player whether or not to include the diminished 7th note. Alternative notations are therefore:
C°7, Cdim7, C°, Cdim
|C°7||C E G B|
|F°7||F A C E|
3. Diminished 7th chords (in equal temperament) contain equal intervals of three semitones between their notes. Because of this, there are only three which are enharmonically distinct. Consider for example C°7 and F°7. The collection of notes in these chords are equivalent - allowing for the enharmonic equivalence of the pairs (G, F) and (B, A).
|C°7||C E F A|
4. Possibly partly for this reason, when one encounters the chord notes written out it is commonest to see them written with "simpler" enharmonic
|C+||C E G|
|E+||E G B|
Augmented triads are formed with a major third and an augmented fifth above the root.
1. Alternative notations are C+, Caug
2. These chords contain an equal interval of four semitones between their component notes and so there are only four of them
which are enharmonically distinct.
|C7+||C E G B|
|E7+||E G B D|
Augmented seventh chords are formed by adding a minor seventh to an augmented triad, or alternatively by augmenting the 5th of an ordinary seventh chord.
Alternative notations include
C7+, C7aug, C7+5, C75, C+7, Caug7
These all reflect the notion that an augmented seventh chord is a seventh chord whose 5th has been augmented (or "sharpened").
|C9+5 C95||C E G B D|
|C9-5 C95||C E G B D|
The +5 or 5 notation of the above example can be added in other circumstances to indicate that the 5th of a chord is augmented (sharpened) and correspondingly -5 or 5 can be added to indicate that the 5th of a chord is diminished (flattened).
Minor chords essentially never have an augmented 5th as (C E G) is enharmonic with (C
E A) which is an inversion of the chord A and the latter is certainly what one hears
when these three notes are played together.
|Cm7-5 Cm75||C E G B|
A special case of the above is a diminished triad with a minor seventh added.
This is often called the "half diminished" seventh chord as it is like a diminished seventh except that only the 5th is diminished instead of both the 5th and the 7th. There is a special alternative notation for it:
|C79||C E G B D|
|Em79||E G B D F|
It is equally possible to alter many of the above chords chromatically. For example if we add a minor ninth instead of a major ninth, the result is often notated "7b9"
The above form is probably the commonest notation today. Other alternatives abound. C-9 (ie like C9 but with the 9th
flattened) was once common, but may cause ambiguities for people used to seeing "-" indicating a minor chord. The notation C9
cannot be used as that notation would define a normal ninth
chord built on the root C. The notation Em9
is, however, well defined, as is C(9) but the explicit use of the 7 in C79
renders the parentheses unnecessary.
|Cadd9||C E G D|
|Cadd11||C E G F|
An obvious question is how to name a chord where one adds a 9th or 11th to a triad without the 7th. Often the notation "add9"
or "add11" is used. (Cadd13 is not necessary as C6 already does the job.)
|Csus4||C F G|
|E7sus4||E A B D|
A suspended note (or suspension) is one which does not belong to the harmony being played at this moment, but rather which belonged to the immediately previous harmony and has been sustained as the harmony changed. The concept has come from classical music into jazz as that of a "sus" chord. In a sus chord the third of the chord is replaced by another note - usually the 4th, sometimes the 2nd - with the original notion being that it should resolve by changing to the third, albeit a little late. Jazz, of course, is characterised by the fact that such resolutions often do not quite get around to happening and so we obtain the concept of the suspension as a chord in its own right.
Sometimes the "4" is omitted leaving the notation Csus, E7sus.
In contrast with a suspension, where the third is replaced by another note, it is also possible to omit the third altogether.
Nowadays this is known as a "5" chord.
Obviously one can go on building more complex chords, for example with more chromatic alterations, but the above include all which will be commonly seen in (for example) a big band score. Already, as we have seen, the notation is not unique, and as chords become more complex, the vocabulary for notation becomes more involved and less well defined. For example the notation CΔ9 may be used to indicate a Cmaj7 chord with an added (major) 9th. Sometimes a guitar or banjo part will simply show diagrams of which strings are to be fingered where - which is one way to avoid the complexities of naming the more involved chords.
The point is that this notation (as all musical notation) has evolved to meet a need and it is therefore rather irregular in places. Nevertheless it is useful.