A heptatonic scale is a musical scale with seven pitches per octave. Among the most famous of these are the major scale

Major scale

In music theory, the major scale or Ionian scale is one of the diatonic scales. It is made up of seven distinct notes, plus an eighth which duplicates the first an octave higher. In solfege these notes correspond to the syllables "Do, Re, Mi, Fa, Sol, La, Ti/Si, ", the "Do" in the parenthesis at...

, C D E F G A B C; the melodic minor scale, C D E F G A B C ascending, C B A G F E D C descending; the harmonic minor scale, C D E F G A B C; and a scale variously known as the Byzantine, Hungarian, gypsy, or Egyptian scale, C D E F G A B C. South Indian (Carnatic music

Carnatic music

Carnatic music is a system of music commonly associated with the southern part of the Indian subcontinent, with its area roughly confined to four modern states of India: Andhra Pradesh, Karnataka, Kerala, and Tamil Nadu...

) classical theory postulates seventy-two melakarta, seven-tone scale types, whereas Hindustani classical music

Hindustani classical music

Hindustani classical music is the Hindustani or North Indian style of Indian classical music found throughout the northern Indian subcontinent. The style is sometimes called North Indian Classical Music or Shāstriya Sangeet...

 postulates twelve or ten (depending on the theorist) seven-tone scale types collectively called thaat.

Diatonic scale

The term diatonic scale refers to a pitch collection and does not imply any particular tonal center, mode or note of special emphasis. It is in this respect different from the term major scale

Major scale

In music theory, the major scale or Ionian scale is one of the diatonic scales. It is made up of seven distinct notes, plus an eighth which duplicates the first an octave higher. In solfege these notes correspond to the syllables "Do, Re, Mi, Fa, Sol, La, Ti/Si, ", the "Do" in the parenthesis at...

, which does imply a tonal center.

Melodic minor scale

In traditional classical theory the melodic minor scale has two forms, as noted above, an ascending form and a descending form. Although each of these forms of itself comprises seven pitches, together they comprise nine, which might seem to call into question the scale’s status as a heptatonic scale. In certain twentieth-century music, however, it became common systematically to use the ascending form for both ascending and descending passages. Such a use has been notably ascribed to the works of Bela Bartok

Béla Bartók

Béla Viktor János Bartók was a Hungarian composer and pianist. He is considered one of the most important composers of the 20th century and is regarded, along with Liszt, as Hungary's greatest composer...

 and to bop and post-bop jazz

Jazz

Jazz is a musical style that originated at the beginning of the 20th century in African American communities in the Southern United States. It was born out of a mix of African and European music traditions. From its early development until the present, jazz has incorporated music from 19th and 20th...

 practice. The traditional descending form of the melodic minor scale is equivalent to the natural minor scale in both pitch collection (which is diatonic) and tonal center.

Harmonic minor scale

The harmonic minor scale is so called because in tonal music of the “common practice period” (from approximately 1600 to approximately 1900) chords or harmonies are more commonly derived from it than from either the natural minor scale or the melodic minor scale. The augmented second between its sixth degree and its raised (“leading tone”) seventh degree, usually traditionally considered undesirable, is easily avoided by distributing these pitches among voices. In the chord progression, D F A, B F G, C E G, (ii⁰, V7, i in C minor) for example, the Ab in the upper voice never ascends to B, and the B in the lower voice never descends to A.

Heptonia Prima and Secunda

The rather unwieldy name of Heptonia Prima and Heptonia Secunda are given to the various seven-note scales which can be formed using tones and semitones but without two semi-tones appearing in succession. Some are more theoretical than others. They are

Heptonia Prima

Beginning on keynote A and working up the notes of the 'natural minor' scale (A, B, C, D, E, F, G, A), the seven modes are:

• Aeolian mode (natural minor) t-s
  Semitone
  A semitone, also called a half step or a half tone, is the smallest musical interval commonly used in Western tonal music, and it is considered the most dissonant when sounded harmonically....
  
  -t-t-s-t-t

• Locrian mode s-t-t-s-t-t-t

• Ionian Mode (major) t-t-s-t-t-t-s

• Dorian Mode t-s-t-t-t-s-t

• Phrygian Mode s-t-t-t-s-t-t

• Lydian Mode t-t-t-s-t-t-s

• Mixolydian Mode t-t-s-t-t-s-t

It may be noted that the Dorian is exactly the same descending as ascending. The less common series is

Heptonia Secunda

The difference between this and the diatonic modes is that they have two and three tones between each semitone, while these latter modes have one and four.
These are sometimes called modes of the melodic ascending minor since that is the most commonly used scale of this type, but other modes can be produced by starting on the different scale notes in turn.
Thus starting on keynote A as above and following the notes of the ascending melodic minor (A, B, C, D, E, F, G) yields these seven modes:

• 'Melodic ascending minor' t-s-t-t-t-t-s
• 'Phrygian raised sixth' s-t-t-t-t-s-t combines the Phrygian flat second and Dorian raised sixth
• 'Lydian raised fifth' t-t-t-t-s-t-s combines the Lydian fourth with a raised fifth

• 'Acoustic
  Acoustic scale
  In music, the acoustic scale, overtone scale, Lydian dominant scale, or Lydian 7 scale, is a seven-note synthetic scale which, starting on C, contains the notes: C, D, E, F, G, A and B. This differs from the major scale in having a raised fourth and lowered seventh scale degree. It is the fourth...
  
  ' or 'Lydian Dominant' Scale t-t-t-s-t-s-t So-called because close to the scale built on natural overtones and combines Lydian raised fourth with Myxolydian (Dominant) flat seventh
• 'Major minor' scale t-t-s-t-s-t-t Like natural minor (aeolian) but with a major third

• 'Half diminished scale
  Half diminished scale
  The half diminished scale is a musical scale more commonly known as "Locrian 2", name which avoids confusion with the diminished scales and the half-diminished seventh chord . It may be considered Mode VI, the sixth mode, of the ascending melodic minor scale...
  
  ' or 'Locrian sharp 2' scale t-s-t-s-t-t-t This is like the Locrian with a raised second

• 'Altered scale
  Altered scale
  In jazz, the altered scale or altered dominant scale is a seven-note scale that differs from the Locrian mode in having a lowered fourth scale degree. Starting on C, it contains the notes: C, D, E, F, G, A and B. In jazz, the altered scale or altered dominant scale is a seven-note scale that...
  
  ' s-t-s-t-t-t-t Like Locrian with diminished fourth

These modes are more awkward to use than those of the diatonic scales due to the four tones in a row yielding augmented intervals on one hand while the one tone between two semitones gives rise to diminished intervals on the other. For example, the last two modes listed above both have 'Locrian' diminished triads built on their tonics given them unstable tonality while the third mode not only has an augmented fourth a la the Lydian mode but also an augmented fifth making the dominant and subdominant unusable.

Heptonia Tertia

The last group of seven note tone/semitone scales are known as Heptonia Tertia and consist of scales with two adjacent semitones which amounts to a whole-tone scale but with an additional note somewhere in its sequence e.g. B C D E F G A.

Other Heptatonic scales

If the interval of the augmented second is used, many other scales become possible. These include
Gypsy I-bII-III-IV-V-bVI-VII
Hungarian

Hungarian gypsy scale

The Hungarian Gypsy Scale is a name given by different authorities to two different scale forms. The more commonly used of these scales is the fourth mode of the Double harmonic scale , it can be found by sharpening the 4th degree of the harmonic minor scale to introduce an additional gap, or...

 I-II-bIII-#IV-V-bVI-VII
The scales are symmetrical about the tonic and dominant respectively and the names are sometimes used interchangeably.

Phrygian Major

Phrygian dominant scale

In music, the altered Phrygian scale or Freygish scale , featuring an unusual key signature and a distinctive augmented second interval, is the fifth mode of the harmonic minor scale, the fifth being the dominant...

 or Dominant Harmonic Minor I-bII-III-IV-V-bVI-bVII
This differs from the Phrygian in having a major third. It may also be considered to be built on the dominant of the harmonic minor scale.
Harmonic major scale C.png

Verdi's Scala Enigmatica

Enigmatic scale

The enigmatic scale is an unusual musical scale, with elements of both major and minor scales, as well as the whole-tone scale...

 I-bII-III-#IV-#V-#VI-#VII i.e. G Ab B C D E F which is similar to the Heptonia Tertia mentioned above differing only in that the second degree here is flattened.

Melakarta

The postulated number of melakarta derives from arithmetical calculation and not from Carnatic practice, which employs far fewer scale forms. Seven-pitch melakarta are considered subsets of a twelve-pitch scale roughly analogous to the Western chromatic scale. The first and fifth melakarta tones, corresponding to the first and seventh chromatic tones, are invariable in inflection, and the fourth melakarta tone, corresponding to the fifth or sixth chromatic tone, is allowed one of two inflections only, a natural (shuddah) position and a raised (tivra) position. Thus the number of possible forms is equal to twice the square of the number of ways a two-membered subset can be extracted from a four-membered set:

Thaat

Hindustani heptatonic theory additionally stipulates that the second, third, sixth and seventh degrees of heptatonic scale forms (septak) are also allowed only two inflections each, in this case, one natural position, and one lowered (komal) position. Arithmetically this produces 2⁵, or thirty-two, possibilities, but Hindustani theory, in contradistinction to Carnatic theory, excludes scale forms not commonly used.

Chinese Gongche notation

Gongche notation

Gongche notation

Gongche notation or gongchepu is a traditional musical notation method, once popular in ancient China. It uses Chinese characters to represent musical notes. It was named after two of the Chinese characters that were used to represent musical notes, namely "工" gōng and "尺" chě...

heptatonic scale gets a do,re,mi,(between fa and fa♯),sol,la,(between ti♭ and ti) heptatonic scale.