When does one omit the fifth in V7 chord in classical harmony?

1. Can you omit the fifth in a V7 chord?
2. When should I omit the fifth?
3. What is a 7th chord without 5th?
4. Why is the 7th chord diminished?

Can you omit the fifth in a V7 chord?

Never omit any note of a triad or seventh chord except the fifth – and only omit the fifth when you must do so in order to follow rule 1. These principles assume that you have written with the correct ranges and that all the chords actually contain the notes you say they do.

When should I omit the fifth?

In these chords the fifth is essentially “inert”. It does not contribute to the sense of major or minor, nor does it add any interest (tension, dissonance or sense of forward movement) to the sound. Therefore it can typically be omitted quite safely without affecting the stability or tonality of the chord.

What is a 7th chord without 5th?

Shifting the b7th up a semitone to use the D# from the E major scale makes it a major 7th, so this chord becomes an Emaj9 (no 5th), the 'major' referring to the 7th and the 9th being the highest extension – for which we always presume the presence of a 7th, or this would be an add9 chord!

Why is the 7th chord diminished?

Because these chords have no leading tone in relation to the chords to which they resolve, they cannot properly have dominant function. They are therefore referred to commonly as non-dominant diminished seventh chords or common tone diminished seventh chords (see below).