Proton is a positive subatomic particle identical to hydrogen atom nucleus. Proton carries +1e elementary charge and is located only in nucleus. Proton and neutron together form nucleons in atomic nuclei
Invented early radio wave detector, setting world record for wireless telegraphy. Discovered alpha and beta radioactivity, naming them after Greek letters. Discovered principle of half-life and applied it to radiometric dating
Length is a measure of distance in the International System of Quantities. The base unit for length in SI is the metre. Length can refer to most extended dimension of a fixed object
Hydrogen has three naturally occurring isotopes: 1H, 2H, and 3H. 1H and 2H are stable, with 3H having a half-life of 12.32(2) years. Deuterium (2H) contains one proton and one neutron, found in seawater. Tritium (3H) contains one proton and two neutrons, produced in nuclear reactors
Carbon-12 is the most abundant stable carbon isotope, comprising 98.93% of Earth's carbon. Contains 6 protons, 6 neutrons, and 6 electrons. Created through triple-alpha process in stars
Lithium naturally exists as 3Li with two stable isotopes: 6Li and 7Li. Lithium-7 is more abundant on Earth, making up 92.2-98.1% of terrestrial lithium. Both isotopes have unexpectedly low nuclear binding energies