Hi Edwin,

Good question here.

It’s just a half step in between the root of the F chord, and then C/E, and so these two voicings are very smoothly connected by the half step movement (root moving from F to E). If you play C/G in that instance you will hear that it isn’t as smooth as moving from Fmaj to C/E.

We can play slash chords over any note of the chord, but they are most common over the essential chord tones (R-3-5-7), in particular the 3rd and 7th are very common.

We have many other pieces that utilise the technique, here are a few to check out:

https://www.pianogroove.com/jazz-piano-lessons/someone-to-watch-over-me-tutorial/
https://www.pianogroove.com/jazz-piano-lessons/skylark-tutorial/
https://www.pianogroove.com/jazz-piano-lessons/like-someone-in-love-2/

For major chords, you will notice that most often the slash chord is using the 3rd as the bass note, for minor chords it’s also common to have the major 7, to minor 7, to minor 6 which is also known as “the minor line cliche”.

Personally, the most important consideration when playing slash chords is to create a smooth step wise bass line, this is typically achieved by moving the bass line in half steps, and so often this will dictate which note to use under the slash chord.

Here are a couple of other tutorials that you might find useful:

https://www.pianogroove.com/jazz-piano-lessons/slash-chords/
https://www.pianogroove.com/blues-piano-lessons/leading-tones-in-gospel/

I hope that helps Edwin.

Study the lessons above and you will see some patterns on when and how slash notation is best applied.

Cheers,
Hayden