I hope that you’re finding this music theory information informative, and certainly I hope that I’m explaining things in an easy-to-understand way while still providing detail. As always, if you have comments, questions, or suggestions please let me know. In this lesson we’ll start taking a look at chord structures.

Alright, so in this lesson I’m going to talk about chords. Chords are another very important part of music, obviously. As per usual, we’ll discuss chords using the C Major scale.

Building Triads

To build chords off each scale degree, all you really have to do is start on the first note and build chords by stacking every other note on top of each other. In the beginning we’re going to work with triads. A “triad” is a three-note chord.

Okay, starting on the note ‘C’ we’re going to stack every other note; so we’ll skip the next note ‘D’ and stack the E. Then we’ll skip the next note ‘F’ and stack the ‘G’. This gives us C, E, G:

This is known as a C triad. We’ll figure out what kind of C triad it is in a minute. First, we want to continue building triads off of each note of the scale. Starting on ‘D’ will give us D, F, and A:

Going through all the rest of the triads will look like this:

Triads galore! We now have all of the triads associated with the C Major scale. Try playing them on your guitar and hear how they sound. They are all technically the key of C Major, but each chord has a distinct sound.

Triad Types

We now need to figure out what type of chord each triad is (major, minor, augmented, diminished, etc…). To do this we have to go back to my lesson on intervals. (If you need a refresher, go and read the intervals article now.)

If we analyze the intervallic relationships between each note, we know that C to E is a major third, and E to G is a minor third. This relationship (major third followed by minor third) is known as a major triad. So, the above chord is a C Major triad.

Try the same thing with D:

The intervallic relationship of this triad is a minor third followed by a major third. This is known as a minor chord. So, the above chord is a D minor chord.

• A triad with a major third followed by a major third is known as an augmented triad.
• A triad with a minor third followed by another minor third is known as a diminished triad.

If we go back to all of the triads built from the C Major scale, we can now analyze each chord and figure out what type of triad each one is.

Roman Numerals

So within a C Major scale we have three major triads, three minor triads, and one diminished triad. We’re going to hearken back to the days of yore once again and assign each one of these triads a roman numeral. This helps us to quickly determine what chord we are talking about. Where this really comes in handy is when playing jazz. Quite often you’ll find situations where jazz songs (called “standards”) will be played in different keys. Perhaps one person will like to play On Green Dolphin Street in C, but someone else will play it in Eb. These situations – which happen all the time – make it very difficult to memorize tunes. Because of this, many people will memorize a tune according to the roman numerals associated with each chord, rather than the chord name. This way you only have to learn the song once and apply it to any key.

Staring on the first chord we’ll assign roman numerals to each scale degree/chord:

Notice that some of the roman numerals are uppercase, and some are lowercase. This is the music theory way of telling the player what type of chord it is.

• Uppercase numerals represent major chords.
• Lowercase numerals represent minor chords.
• Lowercase numerals with a small circle after it represent a diminished chord.
• Augmented chords (not shown here) will be an uppercase numeral with a small plus sign (+) after it.

Once you’re used to seeing chords represented this way it really makes things very easy. You’ll be memorizing tunes much quicker (though admittedly I’m still working on this one myself).

Seventh Chords (7th Chords)

Do you remember in my intervals article where I was discussing 9th, 11th, and 13th interval degrees? It is with the study of chords that these intervals become most apparent. What we want to do now is build extended chords from the triads and see what we come up with. Using the same skip/stack procedure that we used to build the triads, we want to add one more note to each triad. This will give us “seventh chords.” We call them seventh chords because the top note of the chord is seven scale degrees away from the bottom note (also known as the “root” of the chord). Here are the seventh chords in the C major scale:

As with triads, uppercase and lowercase numerals are used, as are the circle and plus signs to designate diminished and augmented chords, and the number 7 tells us that us that we are dealing with a seventh chord.

Looking at the above seventh chord chart you’ll see “Dom 7” and “½ dim 7.” What is that you ask? Well… “Dom 7” means “Dominant 7th chord” and “½ dim 7” means “half-diminished 7th chord.” For now, keep in mind that a Dominant 7th chord is a major triad with a minor third from the fifth of the chord to the seventh. A ½ diminished 7th chord is a diminished triad with a minor third from the fifth to the seventh. (In jazz circles the ½ diminished chord is known as a “minor 7b5” (minor seven flat five) chord.)

There is also a fully-diminished seventh chord (just called a diminished seventh chord), which are three minor third intervals. There are also many others, but let’s stick with these for now.

Extended Chords

Take each seventh chord and add another interval on top of that – these are ninth chords. For example, a C Major ninth chord is C, E, G, B, D; a D minor ninth chord is D, F, A, C, E. You can do the rest on your own.

11th chords would add a third over the 9th, and 13th chords would add a third over the 11th. 13th chords basically use every note of a particular scale, but stacked in thirds instead of played consecutively as you would when playing a scale.

Phew! That’s a lot of chord stuff to absorb, but you’re now well on your way. Once we start getting into jazz theory and advanced chord structures all of this information will start coming together and we’ll be making some wonderful music.

Enjoy!