Isotope by Joe Henderson

Overview

Key: C major · Chords used: 12 · Sections: 5

Form: Intro → Solo → Intro → Solo → A Section

Where these chords come from: a chord chart of this song written by a musician and shared on the iReal Pro forums, archived in the iReal Pro forum charts archived in ChoCo (de Berardinis et al., 2023). It's one musician's reading of the song, not a transcription checked against the recording. This page shows that chart as-is: the analysis below is generated directly from it by code, not written by AI. Consecutive repeats of a chord are shown once, and the piano voicings are our playable arrangement of each chord symbol, not a note-for-note transcription.

Section by section

Intro 1

• C7 – A7 – E♭7 – D7
  I7 – VI7 – bIII7 – II7
• G7 – C7 (×2)
  V7 – I7
• F7 – B♭7 – C7 – A7sus4 – A♭7sus4 – Dm7 – G7 – C7 – A7
  IV7 – bVII7 – I7 – VI7sus4 – bVI7sus4 – ii7 – V7 – I7 – VI7

Solo 1

• G♭7 – E♭7
  bV7 – bIII7

Intro 2

Same chords as Intro 1.

Solo 2

Same chords as Solo 1.

A Section

• C7 – F7 – B♭7 – C7 – A7 – A♭7 – G7 – C7 – A7 – G♭7 – E♭7
  I7 – IV7 – bVII7 – I7 – VI7 – bVI7 – V7 – I7 – VI7 – bV7 – bIII7

Chord vocabulary

Chord	Roman numeral	Role	Heard in
C7	I7	Outside the key (chromatic)	Intro, A Section
A7	VI7	Outside the key (chromatic)	Intro, A Section
E♭7	bIII7	Outside the key (chromatic)	Intro, Solo, A Section
D7	II7	Secondary dominant (V/V)	Intro
G7	V7	In the key	Intro, A Section
F7	IV7	Outside the key (chromatic)	Intro, A Section
B♭7	bVII7	Borrowed from C minor	Intro, A Section
A7sus4	VI7sus4	In the key	Intro
A♭7sus4	bVI7sus4	Outside the key (chromatic)	Intro
Dm7	ii7	In the key	Intro
G♭7	bV7	Outside the key (chromatic)	Solo, A Section
A♭7	bVI7	Outside the key (chromatic)	A Section

Harmonic highlights

• B♭7 (bVII7) is borrowed from the parallel key, C minor.
• D7 acts as V/V: it resolves to G7.

Sources & accuracy

• Chords: the iReal Pro forum charts archived in ChoCo (de Berardinis et al., 2023). Community chord chart “Isotope” (credited “Henderson Joe”, style Medium Up Swing) from the forum file linked here, CC BY 4.0 via ChoCo. Artist as credited on the chart.
• Section names: from the chart's own markings: section names written on the chart (Intro, Verse, Chorus…) are kept, and rehearsal letters are shown as “A Section”, “B Section” and so on (the B of an AABA song is called the Bridge).
• Cross-check: the iReal Pro forum charts archived in ChoCo (de Berardinis et al., 2023). Community chord chart “Isotope” (credited “Henderson Joe”, style Medium Up Swing) from the forum file linked here, CC BY 4.0 via ChoCo. Artist as credited on the chart. A separately posted chart of the same song; its chords match this page's closely when both are read in the same key (similarity 94%).
• Chord charts are often written in a key that suits a particular singer or band, so this may not be the key of the original recording.
• Verified: two community charts of this song, posted in different forum threads, agree on its harmony. They're still charts, not transcriptions checked against the recording.
• Rhythm and chord durations aren't shown; each step is one chord change.