A secondary chord is an analytical label for a specific harmonic device that is prevalent in the tonal idiom of Western music beginning in the common practice period, the use of diatonic functions for tonicization.
In the tonal idiom, a song or piece of music has a tonic note and chord, which is based on the root of the key that the piece is in. The most important chords in a tonal song or piece are the tonic chord (labeled as I in harmonic analysis) and the dominant chord (V). A piece or song is said to be in the key of the tonic. In the key of C major, the tonic chord is C major and the dominant chord is G. Chords are named after the function they serve and their position (for example, the "dominant" is considered the most important after the tonic and the "subdominant" is the same distance from the tonic as the dominant but below rather than above) and numbered by the scale step of the chord's base note (the root of the vi chord is the sixth scale step). Secondary chords are altered or borrowed chords, chords which are not in the key. Secondary chords are referred to as the function they are serving and the key or chord to which they function and are written "function/key". Thus, the dominant of the dominant is written "V/V" and read as, "five of five," or, "dominant of the dominant".
Any scale degree with a major or minor chord on it may have any secondary function applied to it; secondary functions may be applied to diminished triads in some special circumstances.
Secondary chords were not used until the Baroque period and are found more frequently and freely in the Classical period, even more so in the Romantic period, and, although they began to be used less frequently with the breakdown of conventional harmony in modern classical music, secondary dominants are a "cornerstone," of popular music and jazz of the 20th century.
Secondary dominant (also applied dominant, artificial dominant, or borrowed dominant) refers to a dominant triad or seventh chord set to resolve to a degree that is not the tonic, with V(7)/V (V of V), the dominant of the dominant, being the most frequently encountered example. The chord a secondary dominant progresses to can be thought of as a briefly tonicized chord; that is the chord that the secondary dominant resolves to, which sounds momentarily like a tonic to the listener. Tonicizations longer than a phrase can be regarded as modulations to a new key (or new tonic).
"The purpose of the secondary dominant is to place emphasis on a chord within the diatonic progression." "Functioning secondary dominants are used when a composer wants to inject a greater feeling of movement into a diatonic progression." The secondary-dominant terminology is still usually applied even if the chord resolution is nonfunctional (for example, the V/ii label is still used even if the V/ii chord is not followed by ii).
The major scale contains seven basic chords, which are designated in harmonic analysis with Roman numerals in ascending order. Since the chord on the seventh scale degree is a diminished triad, it is not considered stable, and so only the other six chords may be treated as temporary tonic chords, and so be eligible for an applied dominant. In the key of C major, those six chords are:
Of these chords, the V (G major) is said to be the dominant of C major (the dominant of any key is the chord whose root is a fifth above the tonic). However, each of the chords from ii to vi also has its own dominant. For example, V (G major) has a D major triad as its dominant. These extra dominant chords are not part of the key of C major as such because they include notes that are not part of the C major scale. Instead, they are secondary dominants.
Below is an illustration of the secondary-dominant chords for C major. Each chord is accompanied by its standard number in harmonic notation. In this notation, a secondary dominant is usually labeled with the formula "V of ..." (dominant chord of); thus "V of ii" stands for the dominant of the ii chord, "V of iii" for the dominant of iii, and so on. A shorter notation, used below, is "V/ii", "V/iii", etc. The secondary dominants are connected with brackets to their corresponding tonic chords.
Note that of the above, V/IV is the same as I. However, as explained below, they are significantly different.
Like most chords, secondary dominants can be classified by whether they contain certain additional notes outside the basic triad; for details, see Figured bass. A dominant seventh chord (notation: V7) is one that contains the note that is a minor seventh above the root, and a dominant ninth chord (notation: V9) contains the note a ninth above the root. For instance, V7/IV, although it is a C chord, is distinct from regular C major because it also contains the note B flat, which is a minor seventh above the root of C, and not part of the C-major scale.
To illustrate, here are the secondary dominants of C major, given as dominant seventh chords. They are shown leading into their respective tonics, as given in the second inversion.
When used in music, a secondary dominant is very often (though not inevitably) directly followed by the chord of which it is the dominant. Thus V/ii is normally followed by ii, V/vi by vi, and so on. This is similar to the general pattern of music wherein the simple chord V is often followed by I. The tonic is said to "resolve" the slight dissonance created by the tritone that is present in the dominant seventh chord (in a V7 chord in C major, a G7 chord, the tritone is between the notes B and F). Indeed, the sequence V/X + X, where X is some basic chord, is thought of by some musicians as a tiny, short modulation, acting as a miniature dominant-tonic sequence in the key of X.
Before the 20th century, in music of Bach, Mozart, Beethoven, and Brahms, a secondary dominant, along with its chord of resolution, was considered a modulation. Since this was a rather self-contradictory description, theorists in the early 1900s, such as Hugo Riemann (who used the term "Zwischendominante"--"intermediary dominant", still the usual German term for a secondary dominant), searched for a better description of the phenomenon.
Walter Piston first used the analysis "V7 of IV" in a monograph entitled Principles of Harmonic Analysis. (Notably, Piston's analytical symbol always used the word "of"--e.g. "V7 of IV" rather than the virgule "V7/IV.) In his 1941 book Harmony Piston used the term "secondary dominant". At around the same time (1946-48), Arnold Schoenberg created the expression "artificial dominant" to describe the same phenomenon, in his posthumously published book Structural Functions of Harmony.
In the Fifth edition of Harmony by Walter Piston and Mark DeVoto, a passage from the last movement of Mozart's Piano Sonata K. 283 in G major serves as one illustration of secondary dominants. Below, the harmony alone is first given, labeled both for the literal names of the chords and for their chord number in the key of G major.
It can be seen that this passage has three secondary dominants, each one followed (as expected) by the chord of which it is the dominant. The final four chords form a back-cycle, ending in a standard dominant-tonic cadence, which concludes the phrase. The brackets drawn below the diagram show each instance in which a dominant is followed by its corresponding tonic.
The harmony is distributed more subtly between the notes, and goes faster, in Mozart's original:
The secondary dominants here create a rapidly descending chromatic harmony, an effective approach to the tonic cadence at the end of the phrase. There are many similar passages in Mozart's music.
In jazz harmony, a secondary dominant is any dominant seventh chord (major-minor seventh chord) which occurs on a weak beat and resolves downward by a perfect fifth. Thus, a chord is a secondary dominant when it is functioning as the dominant of some harmonic element other than the key's tonic, and promptly resolves to that element. This is slightly different from the traditional use of the term, where a secondary dominant does not have to be a seventh chord, occur on a weak beat, or resolve downward. If a non-diatonic dominant chord is used on a strong beat, it is considered an extended dominant. If it doesn't resolve downward, it may be a borrowed chord.
In some jazz tunes, all or almost all of the chords that are used are dominant chords. For example, in the standard jazz chord progression ii/V/I, which would normally be d minor, G7, C major in the key of C major, some tunes will use D7/G7/C7. Since jazz tunes are often based on the circle of fifths, this creates long sequences of secondary dominants.
Examples include II7 (V7/V) in Bob Dylan's "Don't Think Twice, It's All Right" and III7 (V7/vi) in Betty Everett's "The Shoop Shoop Song (It's in His Kiss)". "Five Foot Two, Eyes of Blue" features chains of secondary dominants. "Sweet Georgia Brown" opens with V/V/V-V/V-V-I. Play (help·info)
An extended dominant chord is a non-diatonic secondary-dominant seventh chord that resolves downwards to another dominant chord. A series of extended dominant chords continues to resolve downwards by perfect fifths until they reach the tonic chord. Most common is the tertiary dominant, which resolves to a secondary dominant. For example, V/V/V (in C major, A(7)) resolves to V/V (D(7)), which resolves to V (G(7)), which resolves to I (note that V/V/V is the same chord as V/ii, but differs in its resolution to a major dominant rather than a minor chord). Quaternary dominants are rarer, but an example is the bridge section of the Rhythm changes which starts from V/V/V/V (in C major, E(7)). Though typically used in jazz, extended dominants have been used in other contexts as well.[vague]
In music theory, a secondary leading-tone chord or secondary diminished seventh, as in seventh scale degree or leading-tone, is a secondary chord but rather than being a dominant it is a leading-tone seventh chord or triad, which are similar in function to dominant chords. Also similar to secondary dominant chords they are altered chords. In contrast to secondary dominant chords they do not move in circle progressions but rather resolve up by half step. Fully diminished seventh chords are more common than half-diminished seventh chords and one may also find diminished triads [without sevenths].
For example, viiø7/V or viio7/iv. The chord progression viio7/V--V--I is quite common in ragtime music. Especially in four-part writing, the seventh should resolve downwards by step and if possible the lower tritone should resolve appropriately, inwards if a diminished fifth and outwards if an augmented fourth. When viiø7 resolves conventionally the chord it resolves to is tonicized: "A secondary dominant is like a miniature modulation; for just an instant, the harmony moves out of the diatonic chords of the key." Secondary leading-tone diminished seventh chords are also useful for modulation, all four notes may be considered the root of any diminished seventh chord.
In harmonic analysis secondary sevenths are expressed in the following format:
where x = the correct inversion symbol (figured bass), and y = the root of the chord of resolution as a Roman numeral. Thus, for example, the leading-tone (viio) of the dominant (V), in its third inversion (4
2), is viio4
2/V. Secondary leading tone chords were not used until the baroque period and are found more frequently and less conventionally in the classical period, they are found even more frequently and freely in the romantic period, they began to be used less frequently with the breakdown of conventional harmony, but secondary chords are a, "cornerstone," of popular music and jazz.
In music theory, the secondary supertonic chord or secondary second, is a secondary chord, but rather than being on the dominant it is on the supertonic scale degree and rather than tonicizing a degree other than the tonic, as does a secondary dominant, it creates a temporary dominant. Thus the progression - - .
Examples include ii7/III (F♯min.7, in C major).
The secondary subdominant is IV/x. For example, in C major, the IV chord is F major and the IV of IV chord is B-flat major.
The other secondary functions are the secondary mediant, the secondary submediant, and the secondary subtonic.