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.
The helium and neon atoms both have full outer electron shellsâ¦ the helium atom has two electrons in its first (outer) shell and the neon atom has eight electrons in its second (outer) shellâ¦ but the argon atom only has eight electrons in its third (outer) shell when the third shell can hold up to eighteen electrons.he helium and neon atoms both have full outer electron shellsâ¦ the helium atom has two electrons in its first (outer) shell and the neon atom has eight electrons in its second (outer) shellâ¦ but the argon atom only has eight electrons in its third (outer) shell when the third shell can hold up to eighteen electrons.