Tonicization is the process of making a non-tonic chord sound like a temporary tonic. This is done with chromatic chords called applied chords, or secondary dominant chords (V(7)) and secondary leading-tone chords (viio(7)) borrowed from the temporary key.

Applied chords are notated with a slash. The chord before the slash is the identity of the applied chord within the secondary key, and the chord after the slash is the chord being tonicized. It's read aloud from left to right with the word "of" replacing the slash: V/ii becomes "five of two."

Applied chords nearly always involve accidentals, and especially accidentals that raise the pitch.

Another way of thinking about applied chords is to imagine them as altered versions of the diatonic chord with which it shares a root (for example, ii becomes II♯, which is V/V).

Chapter Playlist

Tonicization is the process of making a non-tonic chord temporarily sound like tonic. It's accomplished using secondary dominant or secondary leading-tone chords (sometimes called applied dominant and applied leading-tone chords). First, we'll learn how to tonicize the dominant, and then we’ll see tonicizations of non-dominant chords.

Tonicizing V

Analyzing tonicization

Secondary dominant chords (V(7)/V)

Example 1 analyzes a passage that temporarily makes V sound like the tonic chord. Example 2 extracts the two chords from Example 1 that participate in the tonicization. We have a C7 chord moving to an F chord, so if we were to analyze these chords without considering the key signature or the context that Example 1 provides, we'd say the two chords represent the progression \mathrm{V^6_5-I} in F major (Example 2a).

Example 1. Tonicization in Joseph Bologne, Six Concertante Quartets, no. 1, II, mm. 1–8.

Example 2. Reduction of the tonicization in Joseph Bologne, Six Concertante Quartets, no. 1, II, mm. 3–4.

If we now reconsider the context that Example 1 provides, we can see that the F major chord functions as V in the excerpt's home key of B♭ major (Example 2b). Indeed, it's the chord that creates the half cadence that ends the first phrase. We know that we haven't changed keys here because, in addition to the half cadence being in B♭ major, the second phrase also begins in B♭ major (it repeats the beginning of the first phrase). The C7 chord, however, clearly doesn't belong to B♭ major—that's what the E♮ accidental in the bass tells us. As we determined in Example 2, the C7 chord is \mathrm{V^6_5} of the F major chord. To represent that in the context of Example 1, we say that the C7 chord is “\mathrm{V^6_5} of V,” and we write “\mathrm{V^6_5/V}.” In other words, the F major chord is V, and the C7 chord is the \mathrm{V^6_5} of that V chord. We've just labeled our first secondary dominant chord!

Secondary leading-tone chords (viio(7)/V)

Tonicization can also be accomplished using secondary leading-tone chords, as in Example 3.

Example 3. Tonicization in Josephine Lang, "Du gleichst dem klaren blanen See," mm. 21–24.

Example 4. Reduction of the tonicization in Josephine Lang.

Example 4 walks through how to understand the relationship between the two highlighted chords in Example 3.

If we were in G major, we would analyze these chords as viio7–I. Recall that when we learned about the leading-tone seventh chord, we discovered that it's common to lower the chordal seventh in major to create a fully diminished seventh chord. That's still true here (notice the E♭!).

The passage in Example 3 is in C major, so we would analyze the G major chord as V, rather than I. That means the F♯o7 chord is viio7 of the V chord. We write “viio7/V” and say “seven diminished seven of five.”

The passage in Example 3 adds a \mathrm{cad.^6_4} to embellish the dominant. That's why the viio7/V doesn't resolve directly to V.

The \mathrm{cad.^6_4} resolves to V7 rather than the V triad. Now we've arrived at the passage in Example 3.

Note: It's rare but possible in classical music to have a half-diminished seventh chord act as an applied chord. It's even less common in jazz, where it's almost certainly an applied ii∅7.

Chromaticism is an indication that tonicization may be present. Since only V(7) and viio7 (or, rarely, vii∅7—see note in sidebar) can create tonicization, one of the most helpful things for determining the label is to ask “what is the quality of the chromatic chord?” The quality determines the label: if the chord is a major triad or dominant seventh chord, it gets the label V(7). If the chord is a diminished triad or diminished seventh chord, it gets the label viio(7).

When you come across a chromatic note, stop and ask the following questions:

Is the chromatic note part of the chord, or is it an embellishing tone?

Part of the chord: move on to question 2

Embellishing tone: label appropriately

What's the quality of the chord?

Major triad or dominant seventh chord: secondary V chord; label is V(7)/x

Diminished triad or diminished seventh: secondary viio chord; label is viio7/x

To determine x above, ask: In what key is the chromatic chord V or viio? Then, determine what Roman numeral the tonic triad of that key would get in the home key of your passage. That Roman numeral is x.

Writing applied chords

Spelling

The video in Example 5 walks through the steps for spelling V7/V, viio7/V, and vii∅7/V in major and minor keys. We recommend you grab a piece of staff paper so you can follow along by pausing the video and trying the exercises yourself. The steps are summarized below:

Determine the root of the chord being tonicized

Pretend this root is the tonic of a temporary key

Spell the top Roman numeral in that key (either V7 or viio7)

https://www.youtube.com/embed/8HRZFpjWx_M

Example 5. Steps for spelling applied chords.

Resolving

The leading tone of the applied chord i