Dominant chords are one of the most enjoyable chords to solo over. Some styles of music rely strongly on the dominant chord. The dominant chord has so many options that you can use to play over it. However, because the chord is so flexible there are challenges to it. We will discuss how you can play over dominant chords and what options you have available to solo over it.
The most common scale that people use to solo over the dominant chord is the Mixolydian. This scale fits to that chord perfectly with hardly any tensions. This is the go to scale for dominant chord. However, this chord can be much more complex than this scale. Typically in jazz you will find people pushing forward and trying new sounds over the dominant chord. If you consider the dominant chord a little bit different, your whole world of soloing will change.
Most dominant chords are part of the altered family. An altered chord is a chord that has chord tones changed. The unaltered dominant chord is 1 3 5 b7 9 11 13. However if you play a dominant chord most of the time any alterations will fit well. If you make the 9th flat or sharp, make the 11th sharp or the 13th flat you now have an altered chord. This means that every single note is available to use to solo over the dominant chord. The hard part, you can play any note and make it sound good, but if you play any notes you want it will sound bad. You need to play those altered notes with a purpose. The best way to do this is to play with a scale.
You have many scales available to use to solo over dominant chords besides the Mixolydian scale. You have the Whole Tone scale, Diminished scale, Phrygian Dominant (5th mode of harmonic minor), Lydian dominant (3rd mode of melodic minor), and many more. These scales mentioned already take up practically all the notes possible. A common scale that is used a lot in jazz is the bebop scale. The Bebop scale is very similar to Mixolydian and allows for more chromaticism in your playing. The Bebop scale would be a great place to start after you are comfortable with the Mixolydian scale.
Dominant chords are a joy to play over and there are so many option that you can use to solo with. Most dominant chords belong to the altered family which makes virtually every note acceptable. The Mixolydian scale is the go to scale for dominant chords, but there are many other options you can use. Some are similar and others are way different from the Mixolydian. Experiment with different scales and find what works for you.