Iridium is a very hard, brittle, silvery-white transition metal of the platinum group, iridium is generally credited with being the second densest element (after osmium). It is also the most corrosion-resistant metal, even at temperatures as high as 2000 °C.
Protons and Neutrons in Iridium
Iridium is a chemical element with atomic number 77 which means there are 77 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 Iridium are 191, 193.
Main Isotopes of Iridium
Iridium occurs in 2 natural isotopes: 191Ir and 193Ir. 193Ir is the most common isotope, having a natural abundance of approximately 62%.
Iridium-191 is composed of 77 protons, 114 neutrons, and 77 electrons.
Iridium-193 is composed of 77 protons, 116 neutrons, and 77 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 Iridium is 77. 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 Iridium is [Xe] 4f14 5d7 6s2.
Possible oxidation states are +3,4.
Most Common Application of Iridium
Iridium is mainly consumed by the automotive, electronic, and chemical industries. Iridium metal is employed when high corrosion resistance at high temperatures is needed, as in high-performance spark plugs, crucibles for recrystallization of semiconductors at high temperatures, and electrodes for the production of chlorine in the chloralkali process.
|Number of protons
|Number of neutrons (typical isotopes)
|Number of electrons
|[Xe] 4f14 5d7 6s2