Who discoverd radioactive dating
When an alpha particle is ejected from a nucleus, the mass number of the nucleus decreases by four units and the atomic number decreases by two units.
Large amounts of new helium are being created all the time through this same process, where the heat and pressure at the core of stars are causing hydrogen atoms to fuse.
Radioactive isotopes are prepared in the lab using bombardment reactions to convert a stable nucleus into one which is radioactive.
Positron (a particle with the same mass as an electron, but a charge of 1 instead of -1) emission isn't observed in natural radioactivity, but it is a common mode of decay in induced radioactivity.
In 1770, Carl Wilhelm Scheele showed that graphite also burned to form carbon dioxide and thereby discovered another form of carbon.
Yet another form of carbon, fullerene, was discovered in 1985 by Robert Curl, Harry Kroto and Richard Smalley.