More chords and keys

Slide the A shape (2100) up one fret and barre the first fret and you have B♭ (3211): many ukulele shapes move.

Seventh and minor chords

Many simple songs end each phrase with a dominant seventh chord, the V chord with one extra note that pulls strongly back to I. In C that is G7 (0212), in F it is C7 (0001) and in G it is D7 (2223). C7 is one of the easiest chords on the instrument: a single index finger on the 1st fret of the A string, turning A into B♭. The minor chords you will meet next are Dm (2210) and Em (0432). Dm is F with one more finger added on the 2nd fret of the C string; Em is a stretch for the ring, middle and index fingers across frets 4, 3 and 2, and many players find it the hardest of the common shapes.

Keys: the same song in a new place

A key is the home note and scale a song is built on, and each key has its own I, IV and V chords. In C they are C, F and G (or G7). In G they are G, C and D (or D7). In F they are F, B♭ and C (or C7). In D they are D, G and A (or A7). Moving a song from one key to another is called transposing. You shift every chord by the same distance: from C to G is seven semitones up, or five down, so C becomes G, F becomes C and G becomes D. Singers transpose to find a key that sits comfortably in their voice, and ukulele players often pick keys whose chords are easy shapes.

Moving shapes

Because every fret is a semitone, a chord shape with no open strings can slide up and down the neck and keep its quality. Move it up one fret and every note rises a semitone, so the chord name rises a semitone too. A shape that uses open strings cannot slide directly, since the open strings stay put; you first replace the nut with your index finger lying flat across the fret, a barre. The A shape, 2100, played one fret higher over a first-fret barre becomes 3211, B♭. The same idea turns the Am shape 2000 into B♭m (3111) and the G7 shape into A♭7. Use the neck below to check: set any frets and the panel names the chord they make, with every matching name when there is more than one.

Why does a seventh chord pull so strongly toward home? G7 contains B and F, two notes six semitones apart. That interval, the tritone, sounds unsettled, and the smallest moves that settle it are B up one semitone to C and F down one semitone to E, which are exactly two notes of the C chord. So G7 to C feels like a door closing. You can hear it on the neck below: strum G7, then C, then try G7 followed by F and notice how much less final it sounds. The progression in the lab is F, B♭, C7, F in 3/4, a waltz in F major where C7 does the same job that G7 does in C.

Choosing a key for singing is mostly about the highest and lowest notes of the melody. If the top note strains your voice, move the song down; if the bottom notes disappear, move it up. Twinkle in C spans from C4 up to A4, three semitones short of an octave, which suits many voices. In G the same melody runs from G4 to E5, higher and brighter. Write the new chords above the old ones before you play, so the shapes are ready rather than worked out in the middle of a bar.