The dominant seventh chord (dominant 7th) is probably the most used tetrad in the musical world. And quite simple actully, because you just need to add a new note (the seventh minor) to your major triad to obtain a new chord of great tension that begs us to drive or resolve into the tonic note of the progression.
When to use a dominant 7th chord
The dominant 7th chord is usually the first chord that to learn when we start studying guitar chords. In fact, This tetrad is so common that it is often referred to directly as a 7th chord or dominant chord.
By the way, when you read the word dominant, what comes to your mind, the fifth degree, right? (if not, take a look at this article right away).
What I am trying to say in the previous paragraph is that in a melodic progression the dominant 7th chord corresponds to the fifth of the key. I other words, it is a tetrad built on the dominant degree of a major scale.
The dominant seventh chord is usually built on the 5th scale degree of a Key.
For examples, in the G Major scale, D is the fifth scale degree, threfore the 7th chord would be D7 (built with the D, F#, A and C notes). An the reason of this is that D is the 5th scale degree of a G.
The result of this harmonization a strongly dissonant chord that stands out from the harmony of a composition. That is why this type of tetrads usually appears in many musical genres, especially in jazz and blues, due to the musical tension that is sought with them.
What is a dominant 7th chord?
A dominant seventh chord is a set of four notes that we build by adding a minor seventh to a major triad. Therefore, it has the following distribution of third intervals:
Minor Third + Major Third + Minor Third
Which gives us as a result the following formula:
1 3 5 ♭7
So, the answer to the question “what makes a dominant 7th chord” would be the following notes:
However, since everything is much better understood with an example, let’s see how we would build the G Seventh Dominant (G7) chord.
We start from the G musical triad we all know (G – B – D):
Now, we are going to add the minor seventh (flattened 7th). How do we find this note? easy, you count 10 semitones (or 5 whole steps) from the root:
You can also count 3 half steps from the fifth because what we are doing is adding a new interval of third to our major triad.
So, the chord will be formed by the tetrad G – B – D – F.
And how do we play g7 chord on the guitar fretboard? Well, we go to our G chord and look for the flat seventh.
C Dominant Seventh chord
Now that you have understood the theory behind these tetrads, let’s analyze the curious case of the C dominant 7th chord.
Do you see something strange in this tetrad?
Do you miss any musical degree?
Notice that in C7 there is no fifth.
Where is the fifth degree, or rather, why isn’t it there?
The C seventh chord above is made up of the following notes:
- The first is the root and tells us what note the chord is.
- The third indicates that it is a major chord.
- The seventh indicates that it is a seventh note.
In summary: the fifth, although it is important, is the least important of the 4 musical notes, so we can do without it.
In any case, you can build a C7 chord with its fifth degree at the 3rd fret:
How to write a dominant seventh chord
Let’s see now how to notate a dominant 7th chord, which is actually quite easy because they are named first with the root note of the chord, followed by the number 7.
Let’s see some examples to make it clear:
- C7: C seventh or C dominant seventh chord.
- D7: D seventh or D dominant seventh chord.
- E7: E seventh or E dominant seventh chord.
- F7: F seventh or F dominant seventh chord.
- G7: G seventh or G dominant seventh chord.
- A7: F seventh or A dominant seventh chord.
- B7: B seventh or B dominant seventh chord.
By the way, you can also find them under the name Xdom7, for example, Cdom7, Adom7, etc.
But honestly, that is very rare to see.
How to play a dominant seventh chord on Guitar
Once we have understood the theoretical explanation of these tetrads, let’s move on to the final: how to construct a dominant 7th chord on the guitar fretboard:
Songs with dominant 7th chords
And with this, we are done (for the moment) with the 7 guitar chords.
Now it’s your turn to practice them and see how they sound. For this purpose, I will recommend you a couple of songs that include them:
- Brown Eyed Girl (D7).
- Paperback Writer (G7).
- Hound Dog (F7 and G7).
- Wonderwall (A7sus4).
In the case of wonderwall chords the dreaded A7sus4 is actually a suspended fourth chord with dominant seventh, a formation more difficult to pronounce than to play.