Ionization smoke detectors use americium as a source of alpha particles. Alpha particles from the americium source ionize air molecules. This makes some particles positively charged and some negatively charged. Because of this shielding, the smoke detector poses no radiation health risk when they are properly handled.

An ICSD smoke detector is composed of a housing made of polyvinylchloride or poly-styrene plastic, a small electronic alarm horn, a printed circuit board with an assortment of electronic components, and a sensing chamber and reference chamber, each containing a pair of electrodes and the radioactive source material.

The isotope of americium used in smoke detectors is americium-241, which decays by α emission to neptunium-237 with a half-life of 432.2 years. The two longest-lived isotopes in this decay chain are uranium-233 (159,200 years) and bismuth-209 (1.9×1019 years).

How they work: Ionization-type smoke alarms have a small amount of radioactive material between two electrically charged plates, which ionizes the air and causes current to flow between the plates. When smoke enters the chamber, it disrupts the flow of ions, thus reducing the flow of current and activating the alarm.

A ton of spent nuclear fuel contains about 100 grams of americium. Americium was named in honor of the American continent and is located just below europium (named after Europe) in the periodic table. Americium was first produced in 1944 during the Manhattan Project by a group led by renowned American chemist Glenn T.

Glenn T. Seaborg

Americium was discovered in 1944 by the American scientists Glenn T. Seaborg, Ralph A. They produced americium by bombarding plutonium-239, an isotope of plutonium, with high energy neutrons. This formed plutonium-240, which was itself bombarded with neutrons.

Curium is a hard, brittle, silvery radioactive metal that tarnishes slowly and which can only be produced in nuclear reactors. Curium is named in honour of Pierre and Marie Curie, who pioneered the study of radioactivity in the final days of the 19th century.

Curium oxidizes easily. It has multiple oxides and forms highly fluorescent complexes with different organic compounds. This metal is very dangerous. It can accumulate in the liver, lungs, and bones and cause cancer.

Curium is a dense and hard transuranic element that is silvery-white in appearance. Curium is the most radioactive element that can be isolated. It is so intensely radioactive that it boils water, making its chemistry difficult to study. It also glows in the dark (see right).

Carbon

Gold gets its English name from the Germanic word gulþa (meaning gold). The Old English word geolu means yellow. In Latin, gold was called aurum. This is why the chemical symbol for gold is Au.