By the time you reach ABRSM Grade 8 Music Theory, the syllabus asks that you understand “all standard diatonic and chromatic chords“.

You will need to be able to recognise each chord and be able to name it.

You will also need to know which chords were in use at any particular time in music history. The chords used in Baroque music were more limited than those used in the Classical era, and with each new musical era the “harmonic vocabulary” was expanded. By the 20th century, literally any combination of notes can be used to make a chord. The ABRSM syllabus is limited to “standard” chords however, which means those that we can name using the words major, minor, diminished and augmented, plus additional 7ths. Any note at all can be added on to a dominant chord.

Up to grade 7 ABRSM, the syllabus covered all the diatonic chords (i.e. chords built using the notes from the scale of the music). In addition, grade 7 included diminished 7th chords and the Neapolitan 6th.

Grade 8 introduces some more chromatic chords with specific names (the augmented 6ths for example), but also requires you to have an understanding of any triad used as a chromatic chord in any key. You are most likely to meet these chords in Question 2 (keyboard reconstruction, usually in a Romantic style), or Questions 4-5 (score analysis). You will not meet these chords in Question 1 (Trio sonatas) and are unlikely to need them in Question 3 (Composition) unless you want to use them.