Major Scales & Key Signatures

A tightly-framed photograph of a woman playing a harp. American harpist Lisa Lynne performs in Morro Bay, California in 2009. A concert harp includes a string for each pitch in the C major scale, with pedals that retune each pitch class up or down one half step.
(Mike Baird | CC BY-2.0)

Within the system of twelve-tone equal tonality, or 12TET, musical pieces often focus on a particular subset of notes, rather than using all twelve pitches equally.

Heptatonic Scales

Most 12TET music is built in a tonality using fewer than twelve pitches. Most 12TET pieces are heptatonic: they primarily use seven of the twelve notes in the chromatic scale.

Measures 5 through 12 of `Cave of the Winds` by Robert Nathaniel Dett, along with a chart showing the frequency of pitches: C 3, C sharp 2, D 27, D sharp 0, E 6, F 0, F sharp 7, G 13, G sharp 2, A 10, A sharp 2, B 16.
Figure 1: Measures 5 to 12 of Cave of the Winds, a 1902 piece by Canadian-American composer Robert Nathaniel Dett, and a histogram showing the frequency of the notes present in the excerpt. Notes C, D, E, F#, G, A and B appear more often than the others.

The most common heptatonic scales are built from two types of intervals: half steps, the distance between two adjacent pitches, and whole steps, which are equivalent to two half steps.

A diagram showing one octave on the piano keyboard starting on C. The intervals from C to C sharp, from E to F and from A sharp to B are labeled as half steps, and the intervals from C to D, from E to F sharp, and from G sharp to A sharp are labeled whole steps.
Figure 2: Adjacent pitches are a half step apart, and intervals spanning two half steps comprise a whole step.

The Major Scale

One of the most common scales in modern music is the major scale, which has half steps between 3 and 4 and between 7 and 1, and whole steps everywhere else.

Figure 3: Major scales can be built using any note as tonic by following the pattern of whole step, whole step, half step, whole step, whole step, whole step, half step.

A major scale can be constructed beginning on any pitch, yielding a unique collection of seven pitches. Music that is centered on a particular note and which uses a major scale built on that note is considered to be in a major key.

Scale Degrees

Individual scale degrees are often referred to with a name which describes their position or character.

Degree Label Reason for Label
1 tonic the key's tonal center
2 supertonic a step above the tonic
3 mediant halfway between tonic and dominant
4 subdominant a fifth below the tonic
5 dominant a fifth above the tonic
6 submediant halfway betwen tonic and subdominant
7 leading tone commonly resolves to tonic

Key Signatures

All major keys other than C major require the use of at least one accidental. To reduce complexity in staff notation, accidentals are typically shown at the beginning of each line of music, rather than adding accidentals to individual notes. These groupings of accidentals are called key signatures.

An accidental in a key signature applies to that pitch class in any octave. Key signatures are traditionally written with a specific order and pattern of accidentals that varies depending on the clef and type of accidental being used.

Figure 4: Major key signatures as traditionally notated on treble, alto, tenor and bass clef staves. While theoretically possible, D#, G# and A# major are impractical and have much simpler enharmonic counterparts.

Key changes in a piece of music are sometimes shown with a new key signature inserted into the notation.

Measures 138 through 141 of Grand Piano Sonata, Op. 3 by Helene Liebmann, showing a change in measure 140 from C minor to C sharp minor.
Figure 5: Measures 138 to 141 of Grand Piano Sonata, Op. 3, a 1811 piece by German composer Helene Liebmann, showing a key change from C minor to C# minor.

The Circle of Fifths

When the major scale is pattern is applied to all twelve keys, patterns emerge regarding how accidentals are added to the key. Music theorists often visualize this with the circle of fifths, a diagram that shows how all twelve keys are related. This diagram can be a helpful reference and can aid in memorization.

Figure 6: The circle of fifths, a diagram showing the relationship between major keys.

Major Scales & Key Signatures: Summary

  • Heptatonic tonalities, which are built upon seven notes, are very common in 12TET music.
    • These scales usually consist of two types of intervals: whole steps and half steps.
  • The major scale is a heptatonic tonality built on a scale pattern with half steps between 3 and 4 and between 7 and 1.
    • A piece built around the major scale is said to be in a major key.
  • Within the major scale, individual notes are given the names tonic, supertonic, mediant, subdominant, dominant, submediant and leading-tone.
  • To simplify notation, music written in a particular key is usually written with a key signature, a collection of accidentals at the beginning of each staff system which apply to all pitch classes in the piece.
    • Theorists often use the circle of fifths, a diagram which lists keys around the perimeter of a circle, to demonstrate the relationship between keys.

Exercises

Exercise 1: Description of Exercise

Exercise 2: Description of Exercise