CHEM1006 Lecture Notes - Lecture 12: Radionuclide, Unified Atomic Mass Unit, Isotopes Of Nitrogen
Document Summary
Isotopes are various forms of an element that have the same number of protons but a different number of neutrons. Such as carbon, potassium, and uranium, have multiple naturally-occurring isotopes. Isotopes are defined first by their element and then by the sum of the protons and neutrons present. Carbon-12 contains six protons, six neutrons, and six electrons; therefore, it has a mass number of 12 amu. Carbon-14 contains six protons, eight neutrons, and six electrons; its atomic mass is 14 amu. While the mass of individual isotopes is different, their physical and chemical properties remain mostly unchanged. Carbon-12 is the most abundant of the carbon isotopes, accounting for 98. 89% of carbon on earth. Carbon-14 is unstable and only occurs in trace amounts. Unstable isotopes most commonly emit alpha particles and electrons. Neutrons, protons, and positrons can also be emitted and electrons can be captured to attain a more stable atomic configuration through a process called radioactive decay.
