In this article https://www.guitar-chords.org.uk/c-major9-chord.html
Why is the 5th missing in the first and second shape, and the 3rd missing in the third shape?
Why are sometimes all the deegrees included and sometimes not?
Thanks
Most of the time it’s because of fingering constraints, we just don’t have enough fingers to reach all of the notes so sometimes certain notes are left out. Where possible it would be the most neutral notes, like the 5th degree that gets omitted, but not always.
Some styles of music, jazz particularly, guitarists will use chords consisting of only three or four notes even where the fingering is possible. This gives a different kind of sound and voicing possibilities without necessarily losing the tonal quality of the chord.
In a band context where there are other instruments playing, it’s less important to play all of the notes, for instance if the bass player is playing the root note then the guitarist could leave out the root of the chord, the note will just be coming from a different instrument. The more instrumentalists there are in a band the more reason there would be to play fewer notes so that some tonal space is left between instruments and things can sound cleaner overall.
Generally speaking, if you omit notes from a chord, as long as the important notes are given priority then we still get the sense of the right sound. For example if we include the root and third then we can determine whether the chord is major or minor, if we then add the most important note, i.e., the 9th if it is a 9th chord, then even without the fifth it should still sound like a 9th chord most of the time.
Thank you for your answer Lee, I understand but I wonder if these chords that don’t include the 5th for example, are named differently.
Yes, no and it depends. Technically you could name them differently but most of the time it depends on context. It might be that the chord in question “should” be played as the full chord but the guitarist either cannot physically play it or might just prefer the sound of a chord with one of more notes omitted and decide it doesn’t alter the song negatively.
You could name the chord differently if you wanted, i.e., C7 (no fifth) or something like that.
I can’t think of an example chord right now but there might be times where omitting a note results in the chord ending up with the same notes as another chord. It’s really up to you to some extent. Some chords do have their notes coincide but we often don’t think about it. For example, C6 and Am7 share the same notes. So do Fsus2 and Csus4, so it’s just about context.
