Chords are a set of three or more different notes played together on a musical instrument or by an ensemble. When written, the notes are placed one atop the other on a bar of staff paper, or one note per staff line in the case of an ensemble score. It is relatively easy to write chords on sheet music, as long as you keep in mind the limitations and advantages of the instruments you are using. All musical references here relate to classical music.
Understanding Your Instrument
Know what chords can be played on the instrument you are writing music for. There are a myriad of instruments that can play chords, from violins and basses to pianos and guitars. Not all of these can play, for instance, a five-note chord, since many string instruments, for example, have only four strings. Pianos, on the other hand, are keyboard instruments that contain many strings to produce musical sounds. Chords containing five notes or more are easily performed on this instrument.
Review some musical theory to better understand the types of chords that you want to write. If you are writing for the piano or the cello, then writing out all the chords may be the most helpful to the musician.
Use alternative ways of writing chords if needed when writing for the guitar. Simply placing dots, indicating notes, on a small version of the guitar fingerboard, placed above the staff lines, allows the guitarist to know where to place his fingers. Look at websites such as Chordbook.com to see how this is illustrated.
Use tablature, if needed. This is especially helpful if the guitarist does not read music. Tablature is a visual means of showing what chords to play. This is done, as stated by the author of Harmony Central, by writing the string letters to the far left, with the string with the highest tone at the top and the string with the lowest tone at the bottom. Extend lines from each letter and a write a number indicating which finger should play which string. You can check out more tablature information at sites such as Harmony Central or books like the "Guitar Chord Bible" by Phil Capone.
Remember a few things about manually writing chords. When you have two notes that are close together, like A and G, make certain each note is written on either side of the stem, A on one side and G on the other. Also, if you have a chord that is attached to a series of other chords, remember that the stems are often pointed upward on the treble clef and downward on the bass clef.
Writing Chords for a Single Instrument
When you're composing chords for a single instrument, keep in mind the effect that you want to have. There are chords that sound better for fast pieces and those that sound better for slower pieces of music.
Write chords that sound appropriate for fast music. For instance, the violin has four strings and in order to play 3-note chords on the instrument, they must be played fast. Consider the last few lines of the "Praeludium and Allegro" by Fritz Kreisler. This a very dynamic and quick-moving section. It would not sound as fast if these were played as 4-note chords since, on the violin, such chords are usually played two notes at a time. Other instruments can, of course, play 4 or more notes very slowly, like the piano in the second movement of Chopin's "Piano Sonata No. 2." The point is to write what is appropriate for the instrument.
Compose chords that are appropriate for slower music. Since they are played two at a time, the 4-note chord on a stringed instrument like the cello, violin or viola can be played in slower music without altering the effect of the piece.
Writing Chords for an Ensemble
Use techniques that you utilized to write for the individual instrument. Note that a violin playing a G, a viola playing an E and a cello playing a C together can be considered a chord. So in an ensemble situation of three or more people, basically all the music is made up of chords being played by different instruments. Keep in mind the timbre and clef of the instruments that you are using. For instance, if you are writing for a string quartet and all the instruments, start out playing a three-note C natural chord with the second violin and viola playing the E, make certain that the way E is written for the viola is different from the way it is written for the violin. To get a better understanding of the types of clefs each instrument uses, check out websites such as the one for Virginia Polytechnical Institute School of Music.
Create chords that are expressive. Think of the beginning chords of the "Air on the G-string" by J.S. Bach. Even though the music is very slow, it is also beautiful and can be used for church serivices, weddings and concerts. Also note the "Passacaglia" by Handel, arranged for violin and viola by J. Halvorsen. This piece has double-stops, or two-note "chords," in the violin and one or two notes "chords" in the viola. The fact that this piece was originally written for harpsichord is evidenced by the necessarily "layered" of sounds of the violin and viola. Both instruments are needed to create the chords which produce the overall impact of the piece.
Test unusual chords on the piano make certain that the notes sound well together. A G-natural chord may be simple enough, but more complex chords that involve a myriad of instruments may need to be listened to on the piano and edited accordingly. Again, make certain that you know the limitations and qualities of the instruments involved, such as their note range and timbre.