We have already been dealing with tones and semitones in previous posts without even realizing it. A SEMITONE is the smallest distance between any two sounds used in Western music. It is the smallest distance between any two adjacent keys on the piano, whether they be black and white, or white and white. We have already touched this concept when learning about sharps, flats, and accidentals.
A TONE (or WHOLE TONE) is equals to two semitones (in the same direction). Pick a note on the keyboard, now find the next semitone to right. Move right one more semitone, and you’ve got a WHOLE TONE. You can do the same thing in the opposite direction.
Now that we have fleshed out the intracacies of the Western concept of a semitone, we can delve a bit further. A semitone comes in two “flavours”: chromatic and diatonic. When a semitone contains two notes with the same letter name, it is called a CHROMATIC SEMITONE. See below for examples of chromatic semitones. As you can easily see, the notes of a chromatic semitone are the same, but one is altered with an accidental.
A diatonic semitone occurs when a semitone contains two notes with different letter names. See below for examples.
A chromatic semitone can be manipulated to be a diatonic semitone and vice versa. Remember, that most notes can be referred to by different note names. For example E# and F are the same note. Take a look at the two intervals below. They are equivalent, but one is a chromatic semitone, and the other is a diatonic semitone. Try to identify tones and semitones on the piano keyboard. The more you practice the easier it will become. It is very important to grasp this concept fully, as it will form the foundation of many future lessons in musical theory.