Hey there, thanks for reaching out - this is a great question!
Technically, you are correct, we are missing one of the notes of the chord (in this case, the fifth). However, on the guitar, sometimes we are limited in the number of notes we can play at one time, depending on the shape of the chord. This is one of those cases.
[br]So the answer is - It is okay to omit notes from a chord! Plenty of instruments do this commonly - not only the guitar. Certain notes in the chord are more important to the overall sound of the chord than others.
In this case, the fifth is omitted from this particular 7th voicing. It turns out that the fifth actually has the least impact on the overall sound of the chord, so it can be omitted and the voicing still sounds like a dominant 7th very strongly. That is because the dominant 7th sound mostly comes from the sound of the major 3rd and minor 7th played against the root.
Another common scenario is to play a voicing that omits the root. This is used especially when playing with other instruments, since most of the time, the bass or keyboard can cover the root of the chord and the guitar can sit on top nicely by playing the "color" notes of the chord.
In jazz, there can be extended chords that contain 6 notes, making it next to impossible to cover all of those notes on guitar! The guitar voicings for these chords usually cover only 3 or 4 of those notes.
Hope this helps!!
Mike
Originally Posted by: jmikekrGoing through Guitar 1 in "I saw her standing there" The E7 chord you show with the root note on the 5th string only has 3 notes in the chord....it is missing the 5th note (B). Without the 5th and only having the root, 3rd and flat 7th, how can that be an E7 chord if you are missing one of the notes?
Thank you in advance.
Keep rockin!
Mike Olekshy
GT Guitar Coach