Major Scale Chords
When you harmonize the major scale by stacking its notes to form chords, you get a sequence of chords that follow the pattern major, minor, minor, major, major, minor, minorb5. In the key of E, the chords are E, F#m, G#m, A, B, C#m, and D#mb5.
The second chord, or “two chord” as you say in music, is naturally minor and represented using lowercase Roman numerals (ii) or the Arabic number two followed by a minus sign (2-). Many songs make use of the minor ii chord, including “Don’t Let Me Down” by The Beatles (E F#m B in E), “Sweet City Woman” by Stampeders (G Am in G), and “What’s Up?” by 4 Non Blondes (A Bm D in A).
2 Chord as Secondary Dominant
While the second chord in a key is naturally minor, sometimes it’s played as major instead. An example of this is the United States national anthem, “The Star-Spangled Banner.” When played in the key of E, its 2 chord, F#m, is played as F# major. In this case, the F# is acting as a secondary dominant by leading to the 5 chord, B. Here you’re borrowing from what happens naturally in the key of B. In B, F# major is the 5 chord, which is called the dominant, that leads to the 1 chord, or tonic, B. This movement can be used in other keys, like the key of E where F#m is played as F# major and used to lead to B.
A secondary dominant 2 chord is also used in the song “Hey, Good Lookin'” by Hank Williams (C D G in C). This song is in the key of C, which naturally has a Dm chord, but it uses a D major that leads to G. This makes sense when you realize D is the dominant 5 chord in the key of G.
“Patience” by Guns N’ Roses (C G A D in G) is played in the position of G major with guitars tuned down a half-step. The 2 chord, Am, is played as A major and used to lead to D, since A is the dominant 5 chord in the key of D.
Non-secondary Dominant 2 Chords
In some songs, major 2 chords aren’t used to lead to 5 chords. Instead, they lead to 4 chords. A good example of this is “Eight Days a Week” by The Beatles. The chords here are D, E, and G. These chords are all in the key of D. D is 1, E is 2, and G is 4. Normally, the 2 chord would be minor, but it’s played as major instead in this song. Rather than leading to A as a secondary dominant, the E major chord is followed by G. In this case, the major 2 chord creates a bright, uplifting sound.
“American Girl” by Tom Petty and the Heartbreakers also uses a major 2 chord in D, this time with the chord progression D E G A or 1 2 4 5. Perhaps Petty was influenced by the earlier Beatles hit when he wrote “American Girl.”
Using a major 2 chord like this can be thought of as temporary Lydian mode. D Lydian mode is the fourth mode of the A major scale. D Lydian mode has a major 1 chord, D, and major 2 chord, E. You can think of “American Girl” and “Eight Days a Week” as being in the D major scale but borrowing from the parallel scale of D Lydian temporarily while the major 2 chord is played. This type of modal mixture is a common composition technique.
For another song in the key of D that uses a major 2 chord, check out “Headed to the Beach” by Carl Wayne Meekins.
Major 2 Chord Chromatic Voice Leading
Something else worth pointing out is the chromatic voice leading that can take place when a major 2 chord is in use. Keeping with the key of D and using the progress 1 2 4 1, the D chord has an A note in it, the E chord has a G# note, the G chord has a G, and the D chord has an F#. These notes create descending semitones A G# G F#. You can create a nice sound by placing the chromatic notes in the upper voicings of the chords.
It’s interesting how you move up from chords 1 to 2 to 4 while the upper voicings of the chord move down. The fact that this chromatic voice leading exists inside this chord progression is one reason why our ears accept the sound of the major 2 chord.
Those are a few examples of how major 2 chords are used in music. Perhaps you’ll be able to use your ear to hear this type of movement in the music you listen to, or maybe you’ll be inspired to use use a major 2 chord in your own compositions.