In music theory, understanding the major scale and its associated chords is fundamental to grasping the structure and harmony of most Western music. The major scale forms the basis for keys, which provide the framework for compositions. This post explores the C major scale, delves into the function of each chord built on its scale degrees, and explains the principles of functional harmony that guide chord progressions.
The C major scale is one of the most common and straightforward scales in Western music, consisting of the notes C, D, E, F, G, A, and B. It follows a specific pattern of whole and half steps: whole, whole, half, whole, whole, whole, half. This sequence of intervals creates a balanced and harmonious scale that serves as the foundation for building chords and understanding musical keys. In the context of the C major key, each note of the scale serves as the root for a triad, forming a distinct pattern of major, minor, and diminished chords that we will explore in detail.
In music theory, a key is a group of pitches, or scale, that forms the basis of a music composition. Each key has a tonic note and corresponding scale, around which the harmony is centered. The table below outlines the chords, their scale degrees, and their primary functions within the C major key. Understanding these roles helps in creating harmonious and cohesive chord progressions. The tonic (I) serves as the home chord, providing stability and resolution. The supertonic (ii) and subdominant (IV) act as predominant chords, preparing for the dominant (V), which creates tension and drives the progression towards resolution back to the tonic. The mediant (iii) and submediant (vi) add color and connect other chords, while the leading tone (vii°) creates a strong pull towards the tonic due to its inherent dissonance.
| Function | Definition | Chord | Description |
|---|---|---|---|
| Tonic (I) | First scale degree, “home” chord | C major (C, E, G) | Provides resolution, stability, and rest. |
| Supertonic (ii) | Second scale degree | D minor (D, F, A) | Acts as a predominant, sets up the dominant (V). |
| Mediant (iii) | Third scale degree | E minor (E, G, B) | Adds color, connects chords. |
| Subdominant (IV) | Fourth scale degree, predominant | F major (F, A, C) | Prepares for the dominant chord. |
| Dominant (V) | Fifth scale degree | G major (G, B, D) | Creates tension, resolves to tonic (I). |
| Submediant (vi) | Sixth scale degree | A minor (A, C, E) | Contrasts tonic, leads to ii or aids modulation. |
| Leading Tone (vii°) | Seventh scale degree | B diminished (B, D, F) | Strong pull to tonic (I), due to dissonance. |
A key is a group of pitches based on a specific tonic note, which defines the harmonic and melodic framework of a piece of music. It includes a scale, but also encompasses the relationships and functions of chords within that scale, establishing a tonal center (the tonic) around which the music revolves. The key dictates the diatonic chords that naturally occur and their functional roles within the harmony.
A scale is a sequence of notes in a specific order of whole steps and half steps. It provides the pitch material for a key. For example, the C major scale consists of the notes C, D, E, F, G, A, and B. The pattern of intervals between these notes defines the major scale.
Functional harmony refers to the way chords interact and fulfill specific roles within a key to create a sense of movement, tension, and resolution in music. In the context of a key, certain chords are built on each scale degree, and these chords have specific qualities (major, minor, diminished) and functions.
Functional harmony guides the progression of chords in a way that creates musical coherence. For example for C major, a common progression might be I – IV – V – I (C – F – G – C), where:
The qualities (major, minor, diminished) of these chords are determined by the intervals between the notes. These qualities give each chord its unique sound and functional role within the key:
The pattern of major, minor, minor, major, major, minor and diminished triads is consistent in any major scale due to the specific sequence of whole and half steps in the scale.
In the example of the key of C major: