In flame tests, the ammonium ion yields which color?

• A. Yellow
• B. Violet
• C. Green
• D. No color

Answer: (D)

Flame tests rely on emission from energized electrons in metal ions; the color you see comes from photons released as those electrons transition between energy levels. The ammonium ion isn’t a metal ion and doesn’t have the type of electronic transitions that produce a bright visible color. When ammonium salts are heated, they decompose to ammonia, which is colorless in a flame. So, the ammonium ion itself yields no distinct flame color. If other colored metal ions are present in a compound, they would show their characteristic colors, but ammonium alone gives a colorless flame.