Estimated reading time 3 minutes
Table of Contents
Introduction
Are you confused about the difference between the root and the tonic in music theory? Some musicians treat the terms root and tonic as if they were interchangeable. However, they have different, but equally important roles in music theory. Keep reading to learn the difference between the tonic vs. root in music theory.
For a review of Roman numeral analysis:
This article uses musical terms. For definitions, see the Glossary at the end of the post.
Tonic vs. Root in Music Theory #1: Scale Degrees and Root Note Defined
Mobile users: for best results reading the examples, tilt your screen 90o to the right.
Diatonic Chords in C Major:
Before we talk about the tonic vs. the root in music theory, we need to discuss the names for the scale degrees and define the word “root.”
We call the notes in a scale the scale degrees. Each scale degree gets named and numbered. For instance, in C major we have:
- Tonic = 1st scale degree = C (tonic = root of I chord)
- Supertonic = 2nd scale degree = D (supertonic = root of ii chord)
- Mediant = 3rd scale degree = E (mediant = root of iii chord)
- Subdominant = 4th scale degree = F (subdominant = root of IV chord)
- Dominant = 5th scale degree = G (dominant = root of V chord)
- Submediant = 6th scale degree = A (submediant = root of vi chord)
- Leading tone = 7th scale degree = B (leading tone = root of viio chord)
The root note will provide the letter that names the chord. Thus, the note C will be the root of the C major chord.
Tonic vs. Root in Music Theory #2: Why Did They Choose These Names for the Scale Degrees?
Why did they use names like tonic or dominant vs. root in music theory for the scale degrees? The names for the scale degrees describe either their position or their function within the scale.
- Tonic: We call the first scale degree the tonic, because the I chord acts as our relaxing “home” chord.
- Dominant: We call the fifth scale degree the dominant because the V chord strongly leads back to the tonic chord. So, it “dominates” the chord progression.
- Subdominant: The dominant sits five notes above the tonic. Likewise, the subdominant sits five notes below the tonic. Thus, the subdominant is the dominant below.
- Mediant: The word mediant means “middle.” Therefore, the mediant is the “middle note” between the tonic and dominant.
- Submediant: Just as the subdominant is the dominant below the tonic, so the submediant is the mediant below the tonic.
- Leading Tone: The leading tone strongly leads up to the tonic.
- Supertonic: Just as superman is above your average man, so the supertonic sits above the tonic note.
The Roman Numeral Analysis Centurion
Tonic vs. Root in Music Theory #3: How Do We Use Scale Degree Names vs. Root Note Names?
To understand the difference between the tonic and root in music theory, you must understand how the role of the scale degree names differs from the role of root notes.
The name root describes a note’s position within a chord.
- If you look at the chart above, we have one chord built on each note of the scale.
- The lowest note of each chord on the chart we call the root of that chord.
- In any key, we have seven roots, one for each chord.
- However, in each key, you’ll only have one tonic note.
Why do they give the scale degrees names?
- It allows you to abstract from the specific notes of a key and talk about the larger patterns… sort of like in math. (4 apples + 3 oranges = 7 pieces of fruit vs. a + b = c)
- For example, in the keys D and A major, the tonic notes will be different (D vs. A). However, they’ll still behave like the tonic regardless of the key.
- So, the scale degree names allow us to talk about how the notes of the major scale behave in any key.
Plus, you can track notes in chords and chord progressions with them. For example, the tonic note will be the root of the I chord, the fifth of the IV chord, and the third of the vi chord.
So, in each key you have seven roots, but only one tonic, because they have different roles in analyzing music.
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© 2023 Geoffrey Keith
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