Since this element has 50 electrons you know that it has 50 protons. The number of proton= the atomic number. Atomic number 50 is tin. The atomic symbol for tin is Sn and the weight is 120. So this is the tin 120 isotope
Allergies arise when a foreign material such as pollen, bee venom or pet dander responds to your immune system or a food that in most people does not cause a reaction. Substances known as antibodies are formed by your immune system.