Lead-212 and Lead-208 are nuclides of lead. A nuclide is an atomic species that is defined by the constitution of its nucleus. Nuclides refers to a nucleus than to an atom. Each of the two lead nuclides have different number of neutrons.
John Dalton, J.J. Thompson, Ernest Rutherford, Niels Bohr, James Chadwick and Ernest Schrodinger each contributed greatly to the modern atomic theory by finding the actual evidence.
I mean it’s probably not a but you didn’t show a picture.
A crewed space flight is a flight with people in it, an uncrewed space flight is a space flight without people
