Atomic Structure Elements and Isotopes

The nucleus of the first element, hydrogen, consists only of a proton. The second, helium, has two protons and two neutrons. The third, lithium, has three protons and three neutrons, and so on (Fig. 1.2). The atomic weight, measured as daltons (Da), is the sum of the number of protons and neutrons in an element s atomic nucleus. Hydrogen has a mass of 1 Da (the mass of a proton). Helium has two protons and two neutrons to hold the protons together. It therefore has a mass of 4 Da. Lithium has three protons and three neutrons and therefore a mass of 6 Da (Fig. 1.3). Oxygen has an atomic number of 8 and atomic mass of 16. 

Isotopes are elements possessing different numbers of neutrons. Deuterium, a hydrogen atom containing a neutron in addition to a proton, has the same chemical properties as 

1 Necessary Basics Elements, Isotopes, Ions, Chemical Reactions, Energy Metabolism, and Bacterial Structures 

The (3-particle is a radioactive emission. (Diagram prepared by Dr Wirsig-Weichmann) 

By the third decade of the twentieth century, the emitted radioactivity from artificially synthesized tritium (3H) and carbon-14 (14C) was used to follow biochemical reactions. Glucose, amino acids, and other chemical compounds were synthesized with 3H or 14C incorporated either randomly or at some known position in the molecule. The radioactive products derived from radiolabeled glucose or amino acids added to cells, tissue slices, or a whole organism identified the metabolic fate of these molecules under defined 

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