Give an example of isotope

Answer 1

For example uranium has 3 natural isotopes, all radioactive U-234, U-235, U-238.

Also hydrogen has 3 natural isotopes: H-1, H-2 (deuterium), H-3 (tritium) and 3 artificial isotopes; H-4, H-5, H-6.

All the chemical elements has isotopes, stables or radioactive, naturals or artificial.

like oxygen have 3 isotopes O-16,O-17,O-18.

lithium have 2 isotopes like Li-6,Li-7.and many other like magnesium have 3 natural isotopes,Mg-24,Mg-25,Mg-26.

Answer 2

Uranium-235, formally 92235U, although the 92 and the 235 should be vertically aligned with each other. (We just can't represent that on this site.) The atomic number is the 92, and is the elemental identification that makes the substance, in this case, uranium. The 235 is the Atomic Mass, being the number of protons and neutrons. Since the number of protons is 92, then the number of neutrons is 235 - 92 or 143.

An isotope, formally, is a variation of a element that has the same number of protons but a different number of neutrons. For instance, 92238U is an isotope of 92235U, but with three more neutrons. The number of neutrons does not change the elemental or chemical identity, but it does change the nuclear behavior and stability of the atom.

Not asked, but answered for completeness sake, is the issue of the electrons. In a non ionized state, an atom will have the same number of electrons that it has protons, so 92235U technically means also 92 electrons. If you had two extra electrons, for instance, for a net charge of -2, the symbol would be written as 92235U2-. A more useful example would be the alpha particle, which is a helium nucleus, i.e. without its electrons, which would be written as 24He2+.