Diatonic Chords and Roman Numerals

Diatonic Chords and Roman Numerals: AP Music Theory Study Guide ✨

Welcome, aspiring maestros! 🎓 Ready to dive into the world of diatonic chords and Roman numerals, where each note has a job and every chord tells a story? Let's tune up our brains and get ready to uncover the fascinating (and sometimes quirky) world of music theory! 🎶

Diatonic chords are the chords you get by sticking to the notes of a specific scale, without wandering off to the land of sharps and flats that belong to other keys. For instance, in the key of C major (which, let's be honest, is the "vanilla" of keys), your musical toolbox includes the notes C, D, E, F, G, A, and B. No sharps. No flats. We're keeping it natural—like a hipster's grocery list. 🥑

In a major scale, like C major, there are seven diatonic chords. Each chord is built on one of the seven notes of the scale and is identified using Roman numerals. Here's a quick breakdown:

• The chords built on the first (I), fourth (IV), and fifth (V) scale degrees are major chords. 🎉
• The chords built on the second (ii), third (iii), and sixth (vi) scale degrees are minor chords. 🥺
• The chord built on the seventh scale degree (vii°) is a diminished chord. 😱

Remember, these patterns apply to all major scales. So, mastering one is like having the keys to the musical kingdom!

Let's build some triads in C major, shall we? Here are the steps:

1. Take the C major scale: C, D, E, F, G, A, B.
2. Stack two more notes on each scale degree to form triads.
   • C-E-G (I)
   • D-F-A (ii)
   • E-G-B (iii)
   • F-A-C (IV)
   • G-B-D (V)
   • A-C-E (vi)
   • B-D-F (vii°)

Now, each triad has a quality: major (M), minor (m), or diminished (d), as seen above.

Roman numerals shout out the job titles of chords, indicating both their position (root) and type. Whether the chord is inverted doesn't affect its root. In the key of C major:

• GBD is a V chord.
• Likewise, BDG is still a V chord - just an inverted one. We'll dive deep into this when we explore figured bass in another unit. 📜

Hold onto your music stands; we're going minor! Minor scales bring a different vibe to the table. Here's how things get shuffled:

• Chords on the first (i) and fourth (iv) scale degrees are minor.
• Chords on the third (III), fifth (V), and sixth (VI) scale degrees are major.
• The chord on the second scale degree (ii°) is usually diminished.

But wait, there's more! The seventh scale degree fluctuates based on whether we're using the harmonic or natural minor scale. Like a temperamental artist, it can form a diminished chord (harmonic minor) or a major chord (natural minor).

Using a g minor scale (G-A-Bb-C-D-Eb-F), let’s build the diatonic chords:

• G-Bb-D (i)
• A-C-Eb (ii°)
• Bb-D-F (III)
• C-Eb-G (iv)
• D-F#-A (V) – altered to major by raising the third (F#)
• Eb-G-Bb (VI)
• F-A-C (VII) – this is major in natural minor; becomes diminished with harmonic minor.

Always remember: No naturally occurring augmented chords are lounging around in diatonic scales. They must be altered!

Alright, you've met the chords. Now let's see how they mingle! Chord progressions are like musical stories, guiding listeners through different moods and emotions. Here’s the lowdown on some popular ones:

• Tonic-Dominant Progression: A comfy, stable transition from I (tonic) to V (dominant). It's like arriving at your destination after a pleasant journey.
• I-IV-V Progression: Tonic to subdominant (IV) to dominant. Like a musical relay race, it keeps the energy flowing and is a staple in classical music, as well as rock and blues.

Classical maestros often use more intricate patterns to evoke emotion. Consider Beethoven's Symphony No. 5. Its chord progression is a rollercoaster, starting with tension and dissonance, and finally resolving to the homey tonic chord. 🎢

Inversions and dissonant chords add even more flavor, creating layers of tension and resolution. These tools can turn a simple melody into a rich tapestry of sound and are crucial in classical composition.

Here are some terms you should bookmark in your brain (like a good Spotify playlist):

• Augmented Chord: A spicy three-note chord with two major thirds stacked.
• Diatonic Chords: Chords hanging out within a single key.
• Diminished Chord: A tense, three-note chord with two minor thirds stacked.
• Dominant Seventh Chord: A four-note chord adding a minor seventh to the dominant triad.
• Figured Bass: Baroque shorthand for harmonizing over a bass note.

And many more! These terms will navigate you through the complex landscape of music theory.

Congratulations, musical voyagers! You've now charted the seas of diatonic chords and Roman numerals. You've got the knowledge to decode the magical symphonies and harmonies that have shaped music history. Now, go forth and compose with the confidence of Mozart! 🌟

🦜 Polly wants a progress tracker: Can you spell all the diatonic triads in the key of B major? And, what makes a dominant chord in A major? 🎸

Happy studying, and may your music theory skills be ever in tune! 🎵