A musical chord made up of a root, a major third, a perfect fifth, and a minor seventh is known as the dominant seventh chord. In other words, it’s a major triad with the minor seventh of the chord’s root added on. A “7” is placed immediately after the letter designating the chord in musical chord notation to create the symbol that denotes a dominant seventh. In some cases, the “7” is printed in superscript font.
A dominant seventh chord’s structure can be described as a major triad with a minor seventh added. The root is the note that forms the chord’s foundation. The root is the note that the chord’s other three notes are built around. Although technically, that description could refer to a variety of seventh chords, musicians sometimes refer to a dominant seventh chord as simply “a seventh.”
Forming a major triad is the first step in constructing a dominant seventh. The seventh of the root can be added after the triad has been formed. Take the root note and add a major third and a perfect fifth to form the major triad. To make a major triad on G, for example, play a G along with the major third, B, and the perfect fifth, D. Then, to finish the chord, add the root’s minor seventh, which in this case is an F.
Half steps are another way to think about a dominant seventh. In this case, the chord is constructed by playing the root note along with a note four half-steps up from the root, a note seven half-steps up from the root, and a note ten half-steps up from the root. To put it another way, the chord is formed by playing the root, a note four half-steps higher than the root, another note three half-steps higher, and a final note three half-steps higher than the last.
The dominant seventh is known as a chord that sounds “restless” or in need of resolution because the fourth note in the chord, the minor seventh, is at a dissonant interval from the root. There are several options for resolving the chord. A major or minor triad with a fifth below the root is one of the most popular ways to create resolution. A minor triad a major second above the root of the original chord is an alternative resolution that is often equally effective.