Rubidium is a soft, silvery-white metallic element of the alkali metal group, with an atomic mass of 85.4678. Elemental rubidium is highly reactive, with properties similar to those of other alkali metals, including rapid oxidation in air.
Protons and Neutrons in Rubidium
Rubidium is a chemical element with atomic number 37 which means there are 37 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 Rubidium are 85; 87.
Main Isotopes of Rubidium
Rubidium occurs in 2 natural isotopes: 85Rb and 87Rb. Of these, 87Rb is very slightly radioactive, decaying by beta decay with a half-life of 4.9×1010 years. 85Rb is the most common isotope, having a natural abundance of approximately 72%.
Rubidium-85 is composed of 37 protons, 48 neutrons, and 37 electrons.
Rubidium-87 is composed of 37 protons, 50 neutrons, and 37 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 Rubidium is 37. 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 Rubidium is [Kr] 5s1.
Possible oxidation states are +1.
Most Common Compound of Rubidium
Rubidium chloride (RbCl) is probably the most used rubidium compound: among several other chlorides, it is used to induce living cells to take up DNA; it is also used as a biomarker, because in nature, it is found only in small quantities in living organisms and when present, replaces potassium.
|Number of protons||37|
|Number of neutrons (typical isotopes)||85; 87|
|Number of electrons||37|
|Electron configuration||[Kr] 5s1|
Properties of other elements