posted by liz on .
Thanks got through all but one
Element P has an atomic number of 92 and atomic mass of 238. Element s has 92 protons and 143 neutrons.
atomic number and protons are the same would htese two elements be an isotope or different elements
They would be isotopes. Both have atomic number the same, as you point out, so both must be uranium (or the same element as you say). Calculate the mass. Remember mass is number protons + number of neutrons and is the mass number. The first one is listed as 238. The second one requires that you add 92 protons and 143 neutrons = 235 mass number). So one has a mass number of 238 the other one has mass number of 235. Elements having the same atomic number but different mass numbers (or elements with the same atomic number but different number of neutrons) are isotopes.