Simpedia

Ian M., Indiana

Cmaj7 is C, E, G, B.
C7 is C, E, G, Bb. So a dominant 7 chord includes a flatted 7th.
Similarly, Fmaj7 would include E, and F7 would include Eb.

Stephen R., California

The dominant 7th chord would be C7 in the key of F. The Dominant is the 5th scale degree in a key. The 7th that is in that C7 chord is a flatted 7th (Bb). Bb is native to the F Major scale.

Un Mani, Australia

In the vein of great clarity with those pesky 7ths…..Why is the word dominant mentioned. Why not 3rd or tonic/root note?

Karen C., Oregon

The dominant is always the 5th note in the scale, just like subdominant is always the 4th.

Take for instance the G in the C scale, it’s the 5th note. When we make a 7th chord from G we have G B D F, all white notes which fit into the C scale. We don’t call it a “minor” 7th because that is what we call the chord that contains a flatted 3rd (which makes it a minor chord). So we call it dominant 7th, meaning the chord which has at its root the 5th and fits into the scale when the tonic is 5 steps below.

Mark M., New York

There’s something that is potentially very misleading/confusing here that I think is well worth clarifying about this whole “in the key of” thing. Let’s use the key of C as an example. So, fine, in the key of C major, the note G is known as the “dominant.” And, fine, when you start with that note as the root note of a chord and build a 7th chord on top of it by using only notes from the C major scale, you get what’s then called a “G dominant 7th” chord, typically called (and written as) simply “G7.” So, fine, in that sense, G7 is “the” dominant 7th chord in the key of C. But be clear: that’s just the arcane place the chord’s name comes from. When you’re playing a song in the key of C, it’s 100% perfectly allowed/okay/normal/common for multiple dominant 7th chords to be present. They don’t stop being called dominant 7th chords simply because we’re in the key of C where G7 is “the” dominant 7th chord. Yes, fine, all the other dominant 7th chords are named as such because of something having to do with some key/scale other than C major and how that other scale’s notes relate to the notes in that chord in a particular way. So what? Who cares? Doesn’t matter. They’re all just chords, usable in any song, in any key. They’re named for what key/scale they come from — they’re not named for anything having to do with which key a song is in. So hopefully when you hear that G7 is “the” dominant 7th chord in the key of C, you can be clear about just what that means — and just what it doesn’t mean.

Stephen R., California

Can I also add that since multiple dominant 7ths can be used in a given key, they tend to “resolve” to the chord a fifth below it as in Amazing Grace with the 7ths. That’s their role in functional harmony. That’s why those 7ths are in those particular places in Amazing Grace and don’t have arbitrary placement. They’re like transition chords or “pulling” chords, often used to pull us to that final “home” key chord.

Mark M., New York

And it’s important to stress “tend to” because there absolutely are times when dominant 7th chords are not followed by the chord a fifth down from them.

This stuff sure gets messy to talk about, doesn’t it? One helpful thing to remember is that there are simply a whole bunch of different types of 7th chords. Dominant 7th is just one type, happens to be the most commonly used, and therefore is usually referred to as simply a “7th” chord. Which, though convenient from the standpoint of not having to say the word “dominant” every time it comes up, is terribly inconvenient when it comes to getting a handle on the different types of 7th chords — kind of like there being a whole bunch of shades of blue and the most common one just being called blue 🙂 But they’re all blue, not just “blue”!