This isn't a real answer, but an addition to @trw's chord chart.
...I'm confused at the notation, For example the iii and vii chords of the 9ths chords look like Em7(♭9) and Bm7(♭5 ♭9) why do they flat certain notes
The jazz chord symbols - in my assessment - are based upon an assumed diatonic dominant chord that extends up to the 13th. Any chord that isn't a diatonic dominant 13th chord uses various modifiers symbols altering a dominant 13th chord.
G dominant seven
G7, to make a
G minor seven from a
G dominant seven we must change the third to min indicated by the
G dominant nine
G9, to make a
G dominant seven minor nine from a
G dominant nine we must lower the 9th indicated by the
We can compare diatonic
V chords extending all the way up to the 13th and note which intervals above the roots need modification in the
iii chord relative to the intervals above the root of the
root E G root
m13* C E M13
P11 A C P11
m9* F A M9
m7 D F m7
P5 B D P5
m3* G B M3
root E G root
(*) These intervals differ from a diatonic dominant 13th chord and so the jazz chord symbol requires modifiers that detail the changed intervals.
I hope that isn't too confusing changing roots and comparing intervals.
Look back to @trw's chart and notice all the
G chords are simply the root letter
G plus the highest extension number. All the other chords have one or more modifiers for each interval above their roots that is not the same interval above the root of the dominant chords.
The complete list of all diatonic chord with extension up to the 13th, written in jazz chord symbols, is a nightmare! But maybe we can take a step back and look at
vi ii V I which is the practical basis for a lot of jazz harmony.
All four of those chord types start with the root letter and extension figures without any accidentals (except the crazy
Am11b13.) Then only
min is needed for the
maj for the
I. This covers over half of the chart! That isn't too hard to manage.
Less than 1/4 of the chart uses true awful symbols like
Bm11b9b5b13 and they will surely be much less frequently encountered. I don't think you need to worry about instantly recognizing their diatonic identities.