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.
Understanding Triads & Seventh Chords Reference
The most reliable way to build a chord is to begin with the letter names before counting semitones. Chord tones are stacked in thirds, so each new note skips one letter. A chord built from C uses some form of C, E, G, and B.
The exact accidentals decide the quality. This spelling matters because D sharp and E flat may sound the same on a piano, yet they do different jobs on the page.
In a correctly spelled chord, each chord member has its own letter name. This makes music easier to read, analyze, and transpose.
The third gives a triad much of its emotional color. A major third often sounds open or settled. A minor third often sounds darker or more inward.
The fifth affects stability. A perfect fifth supports the root strongly. A lowered fifth creates tension because it divides the octave into two equal parts.
A raised fifth has a bright, floating quality and does not point as strongly toward one key. These sound descriptions are not fixed rules. Context, tempo, rhythm, instrument choice, and melody can change the effect of the same chord.
Seventh chords create stronger harmonic motion because the extra note adds a dissonant interval that usually wants to move by step. In common tonal music, a dominant seventh chord often leads toward a chord built on the next root a fifth below. For example, G dominant seventh tends to move to C major or C minor.
Two notes create much of this pull. The note B tends upward to C, while F tends downward to E or E flat.
This small movement is called voice leading. It explains why chord progressions can sound connected even when several notes change.
Inversions matter most when writing bass lines or arranging music for real instruments. Root position places the root in the bass and gives the clearest sense of the chord's foundation. Other inversions can make the bass move smoothly from one chord to the next.
A guitarist may use an inversion to avoid a difficult jump. A pianist may choose one to keep both hands close together. When identifying a chord, first list all its notes, then find the root by arranging them in stacked thirds.
Finally, note the lowest sounding pitch to name the inversion. Students should practice this process in several keys, sing each chord tone, and listen for which notes feel stable or tense.