In general, we don't play chords per word, Normally chords change at measure/phrase level, depending on the style, however we play notes per melody line syllables.
Check the following answer for some suggestions.
Piano Chord example
More about melody line:
In music, a song will generally have two parts, one is melody and another is chord.
Melody is the song lyric lines that we sing, while chords are the harmony music that supports the melody, normally melody will be played in the higher octave range and chords are played in the lower octave range(if we are just accompanying someone else's vocal, then we play just chords, chord in the higher range and the root of the chord in the lower range). We can assume of the melody as vocal solo and chords as background music to the vocal. In four part songs/chorals, it will have four voices generally the top voice soprano would be the melody line and the lower voices (alto, tenor, bass) would be like chords.
Normally for each syllables in the lyric words, there would be a note (melody note) assigned, (in special cases a syllable would have more that one note(melisma)), but a chord will continue for a measure/phrase,
Try the following lesson
Piano Accompaniment Styles