A chord is nothing more than the union of 3 or more different notes played at the same time. If it’s a union of 3 notes, we call it a triad. If we press 3 different keys of a piano (different meaning that they are not the same note, not even in a different octave), we will have a chord, we won’t know what his name is, but it is a chord.
Depending on how we form the triad (specifically, the interval or number of semitones there is between the notes forming the triad, we will have one type of chord or another. Usually, and this applies to all chords, we will have a “base” note, which we’ll call “tonic”, from which the chord will be named after, and from which semitone distances will be calculated to the other notes of the triad, in order to define the type of chord. In a word, we have 5 types of basic chords, depending on how we form the triad: major, minor, augmented, diminished and suspended. You can forget about the 3 last ones for now, it’s enough for you to know that they exist. Major and minor chord formation, now that is something you must stick in your brain forever. As you are progressing, you will begin to add suspended chords to your vocabulary, then diminished chords, and augmented chords to a lesser extent.
A major chord is always formed by the tonic, a major third and a perfect fifth. A perfect fifth is the note that is 3 tones and a half from the tonic (or seven semitones). They coincide respectively with degrees I, III and V of the major scale. We could also say that a major chord is a part of the major scale, specifically its degrees I, III and V.
Let’s take an example. G major chord is formed by G (tonic), B (major third 2 tones from the tonic), it coincides with degree III of G major scale) and D (perfect fifth, 3 tones and a half from the tonic, it coincides with degree V of G major scale).
Another example, B♭ major chord is formed by B♭ (tonic), D (major third) and F (perfect fifth). Check distances.
A minor chord is formed by the tonic, a minor third and a perfect fifth, that coincide with degrees I, III and V of the minor scale. As you can see, it only differs from a major chord on the third, which is minor (one tone and a half from the tonic), as opposed to the major chord where it is an interval of a major third (two tones from the tonic). This apparently harmless difference completely changes the sound and character of the chord. It is usually designated by a small “m” next to the chord.
As an example, the Am chord is made up of the A (tonic), C (minor third, a tone and a half from the tonic) and E (perfect fifth, 3 tones and a half from the tonic).
An augmented chord is formed by the tonic, a major third and an augmented fifth. An augmented fifth is an interval of 4 tones from the tonic. To put it another way, it is a superposition of 2 intervals of a major third from the tonic. It is an unstable type of chord by nature, they create some kind of tension. They are not used frequently. They are usually designated by adding the “+” sign or “aug” after the chord.
As an example, D+ (or Daug) would be formed by D (tonic), F# (major third) and A# (augmented fifth).
A diminished chord is made up of the tonic, a minor third and a diminished fifth. A diminished fifth is an interval of 3 tones from the tonic. As we saw for the augmented chords, we can also consider diminished chords as being a superposition of two intervals of a minor third. Just like augmented chords, diminished chords create a lot of tension. They are designated by adding the “º” symbol or “dim” after the chord.
For example, the Dº chord (or Ddim), is formed by the D (tonic), F (minor third) and A♭ (diminished fifth). It’s interesting to stress that we didn’t use G♯ to refer to the fifth (although G♯ and A♭ would be enharmonic notes), since the fifth degree of D is A. The G note is the fourth interval.
All the chords we have seen so far have an interval of a third, whether it be a major third (for major and augmented chords) or a minor third (for minor and diminished chords). A suspended chord is a chord on which the interval of a third has been omitted, and where such interval has been replaced by an interval of a perfect fourth or by an interval of a major second. If we use a perfect fourth (2 tones and a half from the tonic), the chord will be called “sus4”. If we use a major second (one tone from the tonic), the chord will be called “sus2”.
These chords can’t be played alone, they create some kind of tension. The lack of a third gives them a sense of being sort of undefined, they are neither major nor minor. On top of that, the intervals of a major second and perfect fourth create a significant dissonance in the chord.
Let’s take a couple of examples. The Dsus2 chord is formed by D (tonic), E (second major) and A (perfect fifth). The chord Dsus4 is formed by D (tonic), G (perfect fourth) and A (perfect fifth)
Let’s briefly introduce the concept of seventh chord. A seventh chord is made up of 4 notes, and is built adding an interval of a seventh to a triad. There are several types of seventh chords, but we are going to focus only on two of them. We will only deal with major triads on which a major seventh or a minor seventh is added, as these are the most common.
If we add an interval of a major seventh (5 tones and a half) to a major chord, we get a major seventh chord. It is designated by adding “maj7” at the end. If we add an interval of a minor seventh (5 tones) to a major chord, we get a seventh chord, usually know as dominant seventh, or plain dominant. They are designated by adding “7” after the chord.
These concepts are quite important to know, it will help you in many situations.
Featured image by Jamille Queiroz (CC0)