It should be noted that all of these decay pathways may be accompanied by the subsequent emission of gamma radiation. Many other rare types of decay, such as spontaneous fission or neutron emission are known. Unstable isotopes decay through various radioactive decay pathways, most commonly alpha decay, beta decay, or electron capture. If there are too many or too few neutrons for a given number of protons, the resulting nucleus is not stable and it undergoes radioactive decay. As a result, as the number of protons increases, an increasing ratio of neutrons to protons is needed to form a stable nucleus. Neutrons stabilize the nucleus, because they attract each other and protons, which helps offset the electrical repulsion between protons. There are only certain combinations of neutrons and protons, which forms stable nuclei. These two forces compete, leading to various stability of nuclei. The neutron has a mean square radius of about 0.8×10−15 m, or 0.8 fm, and it is a spin-½ fermion.Ītomic nuclei consist of protons and neutrons, which attract each other through the nuclear force, while protons repel each other via the electric force due to their positive charge. It has no electric charge and a rest mass equal to 1.67493 × 10−27 kg-marginally greater than that of the proton but nearly 1839 times greater than that of the electron. In the universe, neutrons are abundant, making up more than half of all visible matter. A common oxidation state for simple compounds is +2 (cobalt(II)).Ī neutron is one of the subatomic particles that make up matter. In the periodic table, the elements are listed in order of increasing atomic number Z.Įlectron configuration of Cobalt is 3d7 4s2.Ĭommon oxidation states of cobalt include +2 and +3, although compounds with oxidation states ranging from −3 to +5 are also known. The number of electrons in each element’s electron shells, particularly the outermost valence shell, is the primary factor in determining its chemical bonding behavior. The configuration of these electrons follows from the principles of quantum mechanics. Since the number of electrons and their arrangement are responsible for the chemical behavior of atoms, the atomic number identifies the various chemical elements. Each electron is influenced by the electric fields produced by the positive nuclear charge and the other (Z – 1) negative electrons in the atom. Therefore, the number of electrons in neutral atom of Cobalt is 27. The number of electrons in an electrically-neutral atom is the same as the number of protons in the nucleus. It is useful as a gamma ray source because it can be produced in predictable quantities, and for its high radioactive activity simply by exposing natural cobalt to neutrons in a reactor for a given time. It produces two gamma rays with energies of 1.17 MeV and 1.33 MeV. Cobalt-60 (60Co or Co-60) is a radioactive metal that is used in radiotherapy. Twenty-two radioisotopes have been characterized: the most stable, 60Co, has a half-life of 5.2714 years Ĭobalt-59 is composed of 27 protons, 32 neutrons, and 27 electrons.Ĭobalt-60 is composed of 27 protons, 33 neutrons, and 27 electrons. Main Isotopes of Cobaltĥ9Co is the only stable cobalt isotope and the only isotope that exists naturally on Earth. Mass numbers of typical isotopes of Cobalt are 59. Isotopes are nuclides that have the same atomic number and are therefore the same element, but differ in the number of neutrons. The difference between the neutron number and the atomic number is known as the neutron excess: D = N – Z = A – 2Z.įor stable elements, there is usually a variety of stable isotopes. Neutron number plus atomic number equals atomic mass number: N+Z=A. The total number of neutrons in the nucleus of an atom is called the neutron number of the atom and is given the symbol N. The total electrical charge of the nucleus is therefore +Ze, where e (elementary charge) equals to 1,602 x 10 -19 coulombs. Total number of protons in the nucleus is called the atomic number of the atom and is given the symbol Z. Cobalt is a chemical element with atomic number 27 which means there are 27 protons in its nucleus.

Cobalt electron configuration