Ultrasonic humidifiers are the quietest humidifiers available, and the ideal choice when noise level is a concern (if you are a light sleeper). In general, a warm moisture humidifier will be much quieter than a cool moisture evaporative humidifier.
Iodine is a chemical element with symbol I and atomic number 53. The heaviest of the stable halogens, it exists as a lustrous, purple-black metallic solid at a standard conditions that sublimes readily to form a violet gas. The elemental form was discovered by the French chemist Bernard Courtois in 1811.
Chemical properties. Like the other halogens, iodine is an active element. However, it is less active than the three halogens above it in the periodic table. Its most common compounds are those of the alkali metals, sodium, and potassium. But it also forms compounds with other elements. It even forms compounds with the other halogens. Some examples are iodine monobromide (IBr), iodine monochloride (ICl), and iodine pentafluoride (IF 5 ).