The root of the Major Key is always a Major chord.

In the Key of B♭ Major, where 'B♭' is the root of the Key, the G chord which naturally occurs is the G minor chord, with the notes G-B♭-D, where 'G' is the root (1) of the chord, 'B♭' is the flattened third (♭3) from the chord root, and 'D' is the fifth (5) from the chord root. An 'G' note as the root can then be built into a G Major chord, a G minor chord, a G diminished chord, or a G augmented chord, but only one of these chords will naturally occur in any given Key. This may seem very confusing at first, but the more you learn about keys and chords, and the longer you study, it will make more sense. The root of a key is the name of the key, and the root of a chord is the name of the chord. A Major Key naturally has 3 Major chords (I, IV, and V), 3 minor chords (ii, iii, and vi), and 1 diminished chord (vii Ο). Diminished and augmented refer to the quality of the fifth in a chord. Major and minor as terms refer to the quality of the third in a chord. An augmented chord (noted as 1 - 3 - ♯5) has a Major Interval (of 4 frets) placed on top of a Major Interval (of 4 frets). A diminished chord (noted as 1 - ♭3 - ♭5) has a minor Interval (of 3 frets) placed on top on another minor Interval (of 3 frets). A minor chord (noted as 1 - ♭3 - 5) has a Major Interval (of 4 frets) placed on top of a minor Interval (of 3 frets). A Major chord (noted as 1 - 3 - 5) has a minor Interval (of 3 frets) placed on top of a Major Interval (of 4 frets). Three note chords made from the root, third and fifth are described by their quality Major, minor, diminished, and augmented. Two or more Intervals played together make a chord. Any two notes played together make an Interval. The chords in a Major Key are chords which are comprised of notes in the key. ← B♭ - C - D E♭ - F - G - A B♭ C - D E♭ - F - G - A B♭ → There are seven octaves of B♭ Major on a 88 Key piano. From the root note they are spaced a whole step (2 frets) to the 2nd note, a whole step to the third note, a half step (1 fret) to the fourth note, a whole step to the fifth note, a whole step to the sixth note, a whole step to the seventh note, and a half step into the octave.

The Key of B♭ Major (B-flat) is comprised of seven of twelve possible notes in an octave.