The trachea, bronchi and bronchioles form the tracheobronchial tree â a system of airways that allow passage of air into the lungs, where gas exchange occurs.he trachea marks the beginning of the tracheobronchial tree. It arises at the lower border of cricoid cartilage in the neck, as a continuation of the larynx. By Bibi Saint-Pol [CC BY-SA 3.0], via Wikimedia Commons. Fig 1.0 â Overview of the tracheobronchial tree.
While relative masses are nice if you want to compare protons, neutrons and electrons to one another, it doesn't tell you what the actual masses of these particles are. In kilograms, the masses are: Neutron = 1.6749286*10-27 kg.
The mass number is the number of protons added to the number of neutrons. Hydrogen only contains 1 proton and no neutrons, so that gives a mass number of 1. However, there are some isotopes of Hydrogen, in other words, some atoms that have more than zero neutrons. For example, Deuterium has 1 neutrons hence an atomic mass of 2 and Tritium has 2 neutrons hence an atomic mass of 3. The number you see for atomic mass in a periodic table is an average of the abundance of the isotopes, which is why it's a decimal like 1.007941.00794 and not a whole number.