An atom that has the same chemical property but a different weight is called an Isotope. All atoms of a single element are chemically alike therefore all isotopes of that element must have the same number of outer electrons. The number of protons present in an atom is called the Atomic Number and identifies the element. The Atomic Number of radon is 86 because it has 86 protons. This concept is not to be confused with Atomic Mass, which is the number of protons and neutrons combined in an atom. Radon has 86 protons and 136 neutrons therefore Radon’s Atomic Mass is 222.
Activity that occurs when one or more neutrons are added to an atom’s nucleus causing instability and the resulting nucleus becomes unsettled or radioactive.
The Nucleus of the atom contains protons and neutrons. Protons and neutrons in the nucleus, and the forces among them, affect an atom’s radioactive properties. Protons are positively charged particles. All atoms of an element (radioactive and non-radioactive) have the same number of protons. Electrons are negatively charged particles that orbit the nucleus as a cloud and balance the positive electrical charge of the protons in the nucleus. Neutrons have no electrical charge and are about 1800 times as heavy as an electron. An Ion is an electrically charged atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge.