Tellurium is a brittle, mildly toxic, rare, silver-white metalloid. Tellurium is chemically related to selenium and sulfur. It is occasionally found in native form as elemental crystals. Tellurium is far more common in the universe as a whole than on Earth. Its extreme rarity in the Earth’s crust, comparable to that of platinum.
Protons and Neutrons in Tellurium
Tellurium is a chemical element with atomic number 52 which means there are 52 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 Tellurium are 122-126.
Main Isotopes of Tellurium
Tellurium occurs in 8 natural isotopes: 120Te, 122Te, 123Te, 124Te, 125Te, 126Te, 128Te and 130Te. 128Te and 130Te are very slightly radioactive, decaying by beta decay with a half-life of 2.2×1024 years and 7.9×1020 years. 130Te is the most common isotope, having a natural abundance of approximately 34%.
Tellurium-120 is composed of 52 protons, 68 neutrons, and 52 electrons.
Tellurium-122 is composed of 52 protons, 70 neutrons, and 52 electrons.
Tellurium-123 is composed of 52 protons, 71 neutrons, and 52 electrons.
Tellurium-124 is composed of 52 protons, 72 neutrons, and 52 electrons.
Tellurium-125 is composed of 52 protons, 73 neutrons, and 52 electrons.
Tellurium-126 is composed of 52 protons, 74 neutrons, and 52 electrons.
Tellurium-128 is composed of 52 protons, 76 neutrons, and 52 electrons.
Tellurium-130 is composed of 52 protons, 78 neutrons, and 52 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 Tellurium is 52. 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 Tellurium is [Kr] 4d10 5s2 5p4.
Possible oxidation states are +4,6/-2.
Most Common Application of Tellurium
The largest consumer of tellurium is metallurgy in iron, stainless steel, copper, and lead alloys. Tellurium is used in alloys, mostly with copper and stainless steel, to improve their machinability. When added to lead it makes it more resistant to acids and improves its strength and hardness. Tellurium is usually added to copper to improve machinability (“free cutting”). ASTM specification B301 has 0.5% tellurium.
|Number of protons||52|
|Number of neutrons (typical isotopes)||122-126|
|Number of electrons||52|
|Electron configuration||[Kr] 4d10 5s2 5p4|
Properties of other elements