As we learned yesterday, the difference between a major chord and a minor chord is the third. (The third is the middle note of the chord.) If you take a major chord and lower the third by a half-step, you turn it into a minor chord.
Now, the difference between the standard major and minor scales is that three notes are a half-step lower in the minor scale. Those notes are the 3rd, 6th, and 7th notes of the scale.
You could say that the major scale contains the notes 1, 2, 3, 4, 5, 6, 7, while the minor scale contains 1, 2, 3♭, 4, 5, 6♭, 7♭. Flat (♭) means a half-step lower.
[one], [four], and [five], are, of course, the three famous chords of rock and roll. In a major key, these three chords are major chords. In a minor key, these three chords are minor chords.
Those three lowered notes in the minor scale happen to be perfectly placed to change those three chords from major to minor. 3♭, is, of course, the third of the [one] chord. 6♭ is the third of the [four] chord. And 7♭ is the third of the [five] chord.
In a minor key, the three main chords are [one]m, [four]m, and [five]m, where the m suffix indicates a minor chord. In the key of C minor, these chords are Cm, Fm, and Gm.
You can rock perfectly well in either major or minor. You might have heard someone say that the major mode is brighter and happier, while the minor mode is darker and gloomier. There is some truth to that, but don't pigeonhole the modes. Both major and minor are suitable for a broad range of moods and expressions.
There is much more to the story of 3-chord rock, and many cracks in the wall between major and minor. We'll get to all those nuances soon. For now, let's enjoy the clear-cut difference between major and minor in these two clips from YouTube:
- Three-chord rock in major: Do Ya by Electric Light Orchestra. This was a hit for Jeff Lynne's earlier band The Move, and an even bigger hit when he rerecorded it with ELO.
- Three-chord rock in minor: Tony Adams by Joe Strummer and the Mescaleros. I'm still sad about Joe's untimely death, but he gave us some great songs in his last few years, like this one from Rock Art & the X-Ray Style. But don't ask me who Tony Adams is or what this song is about.