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Chord Families: Tonic, Subdominant & Dominant

Lesson Transcript
Instructor: Christopher Muscato

Chris has a master's degree in history and teaches at the University of Northern Colorado.

Learn about chord families in music and discover what defines chords as tonic, subdominant, and dominant. Explore the function of chords, the relationship between scales and chords, and the key features of each chord family. Updated: 12/28/2021

The Function of a Chord

Imagine that you're playing chess. You've got a whole bunch of pieces at your disposal, but in order to win, you need to use them correctly. That means that you have to understand the true function of each piece. If you're using your knights to draw out your opponent's pawns but saving your own pawns to attack the queen, well, let's just say that would be an unusual strategy.

We can think about musical composition in the same way. You've got all of these notes and chords at your disposal. Technically, you can arrange them however you want, but unless you understand the function of each chord, your composition may not turn out how you'd hoped. Every chord does something different, and once you get this down you'll be able to create music that will put everyone in check.

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  • 0:04 The Function of a Chord
  • 0:41 Scales & Chords
  • 1:54 Tonic Chords
  • 2:30 Subdominant Chord
  • 3:05 Dominant Chords
  • 4:02 Lesson Summary
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Scales & Chords

When we're looking at chord function, we're talking about chord families, or groups of chords that play the same role in their respective keys. That means that we have to start by refreshing our knowledge on the relationship between keys and notes.

Let's begin with the basics. If a piece of music is written in the key of C, that means it's based on the C major scale (an easy one for us to use, since it has no sharps or flats). The C major scale includes the notes C, D, E, F, G, A, and B (and then it starts over again with C).

However, each of those notes also represents a chord that we can build with. So, rather than understanding the key of C as just a series of notes, it's better for us to understand it as the chords C major, D minor, E minor, F major, G major, A minor, and B diminished.

Every key is like this, composed of chords within that scale. Just as C major holds the first position in the key of C, D major holds the first position in the key of D, and F major holds the first position in the key of F. So when we're talking about chord families (in this sense), we're talking about all the chords that hold the same position in their respective keys. This is important because in each key, the role of each position is basically the same. Three of them, however, define more of the composition than any others.

Tonic Chords

The first (literally) chord we need to get to know is the tonic. The tonic is the root chord of the key. So, in a C major key, the tonic chord is C major. In every key, the tonic chord plays the crucial role of establishing the tonal center of the composition.

Musical composition is all about creating tension and then resolving it, and resolution is achieved by coming back to the tonic chord. Therefore, tonic chords are used to start and end major motifs, movements, and even the entire composition. If you do a good job creating tension, then this chord is what your entire composition will be trying to reach, and when it finally resolves, there will be goosebumps.

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