Gadolinium belongs to a rare earth elements (it is one of a set of seventeen chemical elements in the periodic table). In nuclear industry gadolinium is commonly used as a neutron absorber due to very high neutron absorbtion cross-section of two isotopes 155Gd and 157Gd. Gadolinium is widely used as a burnable absorber, which is commonly used in fresh fuel to compensate an excess of reactivity of reactor core. Gadolinium is produced both from monazite and bastnäsite. Commercially, it is recovered from monazite sand and bastnasite by extraction processes and ion exchange techniques.
Protons and Neutrons in Gadolinium
Gadolinium is a chemical element with atomic number 64 which means there are 64 protons in its nucleus. Total number of protons in the nucleus is called the atomic number of the atom and is given the symbol Z. The total electrical charge of the nucleus is therefore +Ze, where e (elementary charge) equals to 1,602 x 10-19 coulombs.
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. Neutron number plus atomic number equals atomic mass number: N+Z=A. The difference between the neutron number and the atomic number is known as the neutron excess: D = N – Z = A – 2Z.
For stable elements, there is usually a variety of stable isotopes. Isotopes are nuclides that have the same atomic number and are therefore the same element, but differ in the number of neutrons. Mass numbers of typical isotopes of Gadolinium are 154-160.
Main Isotopes of Gadolinium
Gadolinium occurs in 6 natural isotopes: 154Gd, 155Gd, 156Gd. 157Gd, 158Gd and 160Gd. 158Gd is the most common isotope, having a natural abundance of approximately 24%.
Gadolinium-154 is composed of 64 protons, 90 neutrons, and 64 electrons.
Gadolinium-155 is composed of 64 protons, 94 neutrons, and 64 electrons.
Gadolinium-156 is composed of 64 protons, 92 neutrons, and 64 electrons.
Gadolinium-157 is composed of 64 protons, 93 neutrons, and 64 electrons.
Gadolinium-158 is composed of 64 protons, 94 neutrons, and 64 electrons.
Gadolinium-160 is composed of 64 protons, 96 neutrons, and 64 electrons.
Electrons and Electron Configuration
The number of electrons in an electrically-neutral atom is the same as the number of protons in the nucleus. Therefore, the number of electrons in neutral atom of Gadolinium is 64. Each electron is influenced by the electric fields produced by the positive nuclear charge and the other (Z – 1) negative electrons in the atom.
Since the number of electrons and their arrangement are responsible for the chemical behavior of atoms, the atomic number identifies the various chemical elements. The configuration of these electrons follows from the principles of quantum mechanics. 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. In the periodic table, the elements are listed in order of increasing atomic number Z.
Electron configuration of Gadolinium is [Xe] 4f7 5d1 6s2.
Possible oxidation states are +3.
Like most of the rare earths, gadolinium forms trivalent ions with fluorescent properties, and salts of gadolinium(III) are used as phosphors in various applications.
The kinds of gadolinium(III) ions occurring in water-soluble salts are toxic to mammals. However, chelated gadolinium(III) compounds are far less toxic because they carry gadolinium(III) through the kidneys and out of the body before the free ion can be released into the tissues.
Most Common Chemical Compound of Gadolinium
Gadolinium(III) oxide (archaically gadolinia) is an inorganic compound with the formula Gd2O3. It is one of the most commonly available forms of the rare-earth element gadolinium, derivatives of which are potential contrast agents for magnetic resonance imaging.
|Number of protons||64|
|Number of neutrons (typical isotopes)||154-160|
|Number of electrons||64|
|Electron configuration||[Xe] 4f7 5d1 6s2|
Properties of other elements