Review: Diatonic Triads in Major
The primary triads are the basic vocabulary of tonal music. (Tonal music is defined as the music of the Common Practice Period that uses the major and minor tonalities.)
In major keys, the primary triads are the tonic (I), subdominant (IV), and dominant (V).
Secondary triads function as substitutions or elaborations for the primary triads. These are the supertonic (ii), mediant (iii), submediant (vi), and leading tone triad (viio).
To identify a chord and its function within a key, Roman numerals are written below the chord. Major triads are written with upper case letters, minor triads use lower case letters, and diminished triads use lower case letters with a superscript circle (o).
Memorize the qualities of the triads in major keys:
- The primary triads are major (I, IV, V)
- The secondary triads are minor (ii, iii, vi) and diminished (viio)
Practice 1
It is essential to memorize and be able to name triads by degree in all keys. These triads are the basis of all tonal music studies. Using flash cards can be helpful.
Example 1: What is the iii triad in D major?
Answer: The 3rd note of D major is F
. The iii triad in major keys is a minor triad. Therefore, the iii triad in D major (D: iii) is F minor.
Example 2: What is the vi triad in A
major?
Answer: The 6th note of A major is F. The vi triad in major keys is a minor triad. Therefore, the vi triad in A major (A: vi) is F minor.
Example 3: In what major keys does the C major triad exist?
Answer: The only major triads in major keys are the primary triads I, IV, and V. C major is I in C major, IV in G major, and V in F major. Therefore, the C major triad exists in the following keys: C: I, G: IV, and F: V.
Practice 2 and 3