Triads and seventh chords are the basic building blocks of harmony in many styles of music. This cheat sheet helps students quickly identify chord quality, build chords from a root, and understand how added notes change the sound. It is useful for music theory, ear training, composition, arranging, and keyboard practice.
Students in grades 8-12 can use it as a fast reference when reading or writing chord symbols.
Key Facts
- A major triad formula is root + major 3rd + perfect 5th, or 1-3-5.
- A minor triad formula is root + minor 3rd + perfect 5th, or 1-b3-5.
- A diminished triad formula is root + minor 3rd + diminished 5th, or 1-b3-b5.
- An augmented triad formula is root + major 3rd + augmented 5th, or 1-3-#5.
- A major seventh chord formula is root + major 3rd + perfect 5th + major 7th, or 1-3-5-7.
- A dominant seventh chord formula is root + major 3rd + perfect 5th + minor 7th, or 1-3-5-b7.
- A minor seventh chord formula is root + minor 3rd + perfect 5th + minor 7th, or 1-b3-5-b7.
- A chord inversion changes which chord tone is in the bass, but it does not change the chord quality.
Vocabulary
- Triad
- A three-note chord built from a root, a third, and a fifth.
- Seventh chord
- A four-note chord made by adding a seventh above the root to a triad.
- Root
- The note that gives a chord its name and acts as its main reference point.
- Chord quality
- The type of chord, such as major, minor, diminished, augmented, dominant, or major seventh.
- Inversion
- A chord position in which a note other than the root is the lowest sounding note.
- Interval
- The distance in pitch between two notes, such as a third, fifth, or seventh.
Common Mistakes to Avoid
- Confusing major seventh and dominant seventh chords is wrong because Cmaj7 uses B, while C7 uses Bb.
- Calling every four-note chord a seventh chord is wrong because the added note must function as a seventh above the root.
- Ignoring accidentals in the key signature is wrong because chord tones must be spelled with the correct sharps or flats.
- Changing the chord name during an inversion is wrong because C-E-G, E-G-C, and G-C-E are all C major triads.
- Using only keyboard shape instead of interval formula is risky because the same chord quality can look different in different keys.
Practice Questions
- 1 Build an F major triad using the formula 1-3-5.
- 2 Name the chord tones in a D minor seventh chord using the formula 1-b3-5-b7.
- 3 Identify the quality of the chord G-B-D-F.
- 4 Explain why C-E-G-B and C-E-G-Bb have different chord qualities even though they share the same triad.