Chest radiograph. A chest radiograph, colloquially called a chest X-ray (CXR), or chest film, is a projection radiograph of the chest used to diagnose conditions affecting the chest, its contents, and nearby structures. Chest radiographs are the most common film taken in medicine.
Helium is a chemical element with symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas that heads the noble gas group in the periodic table. Its boiling and melting points are the lowest among all the elements.he nucleus of the helium-4 atom is identical with an alpha particle. High-energy electron-scattering experiments show its charge to decrease exponentially from a maximum at a central point, exactly as does the charge density of helium's own electron cloud.
Nitrogen atom structure . Wave theory-United nature theory . Tejman Chaim Henry Dr. Name: Nitrogen Symbol: N Atomic Number: 7 Atomic Mass: 14.00674 amu Melting Point:-209.9 Â°C (63.250008 K, -345.81998 Â°F) Boiling Point:-195.8 Â°C (77.35 K, -320.44 Â°F) Number of Protons/Electrons: 7 Number of Neutrons: 7 Classification: Non-metal Crystal Structure: Hexagonal