Why Do Some Chords Work Together And Some Chords Don't

[NC11-AM] This is a simple lesson for the novice on the subject of Basic Primary and Secondary Chords or what is also sometimes known as the 6 Scale Chords. So why do some chords work well together and some dont ?

To answer that question the first thing we need to do is to take a look at the Major Scale, we'll use C as an example, the Roman Numerals are used to represent the Major Scale positions.

 ROOT                     Sub-Dom  Dominant                  Octave
      I       II       III       IV       V      VI      VII      VIII
      
      C       D         E        F        G       A       B        C

THE 3 PRIMARY CHORDS @ I-IV-V ( C-F-G )

The reason why some chords work is because they belong to a key, in this case C and the most important chords in a Major key are the I Root Chord, the V Dominant chord and the IV Sub-Dominant Chord ( as indicated above ) if you look at the diagram you will see a C at the I and VIII, and in the middle the F and G, by observing the symmetry you get an idea of the magnetic influence of the I and VIII and how it pulls through the centre. All chords want to find their way "home" to the I Root eventually and have varying degrees of magnetism, pulling and pushing their way around the whole scale, none more so than the V and IV, so this is why we call the I, IV and V The 3 Primary Chords, In C @ C, F and G, if you use the Roman numerals you can take a key e.g., G so G is I, A is II thus C is IV and D is V etc etc.

THE 3 SECONDARY CHORDS @ VI-II-III ( Am-Dm-Em )

So we have the 3 most commonly used chords in music but they are all major and where is the Minor?

The first thing we need to do is look at the scale again, and focus on the VI Chord, as this is known as the Relative Minor Root Position, all Major keys have a Relative Minor Key that uses exactly the same notes,& vica versa all minor keys have a relative major key.

So the VI is the Relative Minor Root position to C or "i" which is A minor. If we play in the key of A minor A is i, B is ii, C is iii (Relative Major), D is iv and E is v, hence the 3 minor secondary chords Am,Dm and Em.

THE 6 SCALE CHORDS IN 2 KEYS C AND G

*                  *
      I       II       III       IV       V       VI       VII       VIII  
 
C     C       Dm       Em        F        G       Am  

G     G       Am       Bm        C        D       Em

Where I have indicated with a * these chords also work nicely as 7ths.

So try the 6 Scale Chords in any order you like and experiment.

          PRIMARY CHORDS             SECONDARY CHORDS
In C   C - F - G and / or G7     Am - Dm - Em and / or E7 
in G   G - C - D and / or D7     Em - Am - Bm and / or B7

Just remember that the 6 scale chords belong to both C AND A minor, and both keys have exactly the same notes, but with root positions in different places. When you have spent some time on the 6 Scale chords you can investigate the last chord that completes the set the VII which is Diminished.

Root = I
Dominate = V and vii°
Subdominate = IV and ii (typically from ii-V or IV to vii°)
the iii and vi don't fall into either category but can also easily be used.

you show diatonic chords for the most part except for the III7 in the key of C this would be E7, this technically should be Emin7. E7 contains E G# B F, the G# should be a G if you want to stay in key so Emin7(E G B F) is the chord you want.

you shouldn't only bring up dominate7 chords, you should also show the rest of them, if you're even going to touch on that. maj7 min7 min7(b5) (these ones are the other 7th chords diatonic to the major scale Imaj7 ii7 iii7 IVmaj7 V7 vi7 vii°(b5)) and you could explain dim7 (but I wouldn't yet since it is a bit more complicated)

the roman numerals should also be used as caps (I IV V) for major and lowercase (ii iii vi) for minor. this makes things easier when it comes to chords charts for each key. I ii V progression is clearly Major Minor Major, so when someone gives you this and says key of C (and they don't always specify major or minor and expect you to know which one they want to play) you know its definately C Dmin G.

caps = major chord
lowercase = minor chord

Major key= I ii iii IV V vi vii° not I II III IV V VI VII
Minor key= i ii° III iv v VI VII not i ii iii iv v vi vii

in other words the caps and lowercase do not indicate the key directly, and teaching it this way is setting the noobs up for failure. in your example I ii V in C would be Cmajor D° Gmajor when it means Cmaj Dmin Gmaj.... so here they wil be playing the wrong chords and jamming with others becomes way more difficult.