Major and Minor Triads (Junior Cert Music): Revision Notes

Major and Minor Triads

What is a Triad?

• A triad is a three-note chord made up of:
  1. The Root (the starting note)
  2. The 3rd (the note 3 steps above the root)
  3. The 5th (the note 5 steps above the root)
• Triads are built by stacking intervals of a third. They can be major or minor, depending on the types of intervals used.
• The root gives the triad its name (e.g. C major, A minor).

Major Triads in a Major Key

• In every major scale, major triads are found on:
  • The 1st note – called the tonic
  • The 4th note – called the subdominant
  • The 5th note – called the dominant
• These are the three most important chords in any major key.
• Roman numerals are used to label chords:
  • Uppercase numerals (I, IV, V) are for major triads
  • Lowercase numerals (ii, iii, vi) are for minor triads

Example: C Major

In the key of C major, the major triads are built on:

• C (I) – the tonic triad
• F (IV) – the subdominant triad
• G (V) – the dominant triad | Triad Name | C Major Scale Notes | Triad Notes | |---|---|---| | C major (I) | C – D – E – F – G – A – B – C | C – E – G | | F major (IV) | C – D – E – F – G – A – B – C | F – A – C | | G major (V) | C – D – E – F – G – A – B – C | G – B – D |

Minor Triads in a Major Key

• In every major scale, minor triads occur on the:
  • 2nd note (ii)
  • 3rd note (iii)
  • 6th note (vi)
• In the C major scale (C – D – E – F – G – A – B – C), the minor triads are:
  • D minor (ii)
  • E minor (iii)
  • A minor (vi)
• These triads sound different from major triads because the intervals between the notes are different.

How Are Triads Built?

Major Triad

• From root to third = major third (4 semitones)
• From third to fifth = minor third (3 semitones)

Minor Triad

• From root to third = minor third (3 semitones)
• From third to fifth = major third (4 semitones) This difference in interval structure gives major triads a bright, happy sound and minor triads a sad, darker quality.

Minor vs Major Triad – What's the Difference?

Feature	Major Triad	Minor Triad
Root to Third	Major third (4 semitones)	Minor third (3 semitones)
Third to Fifth	Minor third (3 semitones)	Major third (4 semitones)
Sound	Bright, happy	Sad, dark, emotional

Example: C Minor Triad

• Root = C
• Minor third = E♭ (3 semitones above C)
• Fifth = G (4 semitones above E♭)
• C minor triad = C – E♭ – G
• This interval structure gives the triad its minor sound.