Triads and Seventh Chords
Triads
In music theory, there are four basic types of triad chords: major, minor, augmented, and diminished. Each of these chords is made up of three notes and creates a different mood or feeling.
A major chord sounds happy and strong. It is built using the root note, a major third, and a perfect fifth. For example, a C major chord consists of the notes C, E, and G. C is the root, E is four half steps above C (a major third), and G is seven half steps above C (a perfect fifth).
A minor chord has a sad or emotional sound. It also uses the root and the fifth, but the third is lowered by a half step compared to a major chord. An A minor chord includes the notes A, C, and E. A is the root, C is a minor third (three half steps above A), and E remains a perfect fifth (seven half steps above A).
An augmented chord sounds tense or mysterious. It is created by raising the fifth of a major chord by a half step. For instance, a C augmented chord contains the notes C, E, and G-sharp. C to E is a major third, and G-sharp is eight half steps above C, forming an augmented fifth.
A diminished chord has a dark or unstable quality. It lowers both the third and the fifth from a major chord. A B diminished chord is made up of B, D, and F. B to D is a minor third (three half steps), and F is a diminished fifth (six half steps above B).
Seventh Chords
A seventh chord is a type of chord that builds on a basic triad by adding one extra note: the seventh, which is the seventh scale degree above the root. While a triad has three notes—the root, third, and fifth—a seventh chord includes a fourth note that adds richness, depth, and emotion. The type of seventh added (major or minor) changes the character of the chord, making it sound smoother, darker, or more tense.
There are several types of seventh chords, but four are especially common for beginners. A major seventh chord sounds smooth and jazzy. For example, a C major seventh (Cmaj7) consists of the notes C, E, G, and B. It’s built from a C major triad plus a major seventh (B).
A minor seventh chord has a more relaxed, soulful feel. C minor seventh (Cm7) is made up of C, E♭, G, and B♭—a minor triad plus a minor seventh.
A dominant seventh chord is very common in blues and pop music. It has a major triad with a minor seventh. C7, for example, includes C, E, G, and B♭. It creates tension that makes listeners expect a resolution, often to the F major chord.
Lastly, a diminished seventh chord sounds dark and dramatic. A C diminished seventh (C°7) includes C, E♭, G♭, and A (often written as B double-flat), with all notes spaced by three half steps.
On piano, seventh chords are played with four notes, and they often appear in jazz, R&B, classical, and pop music to add color and complexity. Learning how to use them can make your playing sound much more expressive and sophisticated.
