Rubidium in the context of Laser

Mercury is a chemical element; it has symbol Hg and atomic number 80. It is commonly known as quicksilver. A heavy, silvery d-block element, mercury is the only metallic element that is known to be liquid at standard temperature and pressure; the only other element that is liquid under these conditions is bromine, one of the halogens, though metals such as caesium, gallium, and rubidium melt just above room temperature.

Mercury occurs in deposits throughout the world mostly as cinnabar (mercuric sulfide). The red pigment vermilion is obtained by grinding natural cinnabar or synthetic mercuric sulfide. Exposure to mercury and mercury-containing organic compounds is toxic to the nervous system, immune system and kidneys of humans and other animals; mercury poisoning can result from exposure to water-soluble forms of mercury (such as mercuric chloride or methylmercury) either directly or through mechanisms of biomagnification.

In condensed matter physics, a Bose–Einstein condensate (BEC) is a state of matter that is typically formed when a gas of bosons at very low densities is cooled to temperatures very close to absolute zero, i.e. 0 K (−273.15 °C; −459.67 °F). Under such conditions, a large fraction of bosons occupy the lowest quantum state, at which microscopic quantum-mechanical phenomena, particularly wavefunction interference, become apparent macroscopically.More generally, condensation refers to the appearance of macroscopic occupation of one or several states: for example, in BCS theory, a superconductor is a condensate of Cooper pairs. As such, condensation can be associated with phase transition, and the macroscopic occupation of the state is the order parameter.

Bose–Einstein condensates were first predicted, generally, in 1924–1925 by Albert Einstein, crediting a pioneering paper by Satyendra Nath Bose on the new field now known as quantum statistics. In 1995, the Bose–Einstein condensate was created by Eric Cornell and Carl Wieman of the University of Colorado Boulder using rubidium atoms. Later that year, Wolfgang Ketterle of MIT produced a BEC using sodium atoms. In 2001 Cornell, Wieman, and Ketterle shared the Nobel Prize in Physics "for the achievement of Bose–Einstein condensation in dilute gases of alkali atoms, and for early fundamental studies of the properties of the condensates".

The alkali metals consist of the chemical elements lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), and francium (Fr). Together with hydrogen they constitute group 1, which lies in the s-block of the periodic table. All alkali metals have their outermost electron in an s-orbital: this shared electron configuration results in them having very similar characteristic properties. Indeed, the alkali metals provide the best example of group trends in properties in the periodic table, with elements exhibiting well-characterised homologous behaviour. This family of elements is also known as the lithium family after its leading element.

The alkali metals are all shiny, soft, highly reactive metals at standard temperature and pressure and readily lose their outermost electron to form cations with charge +1. They can all be cut easily with a knife due to their softness, exposing a shiny surface that tarnishes rapidly in air due to oxidation by atmospheric moisture and oxygen (and in the case of lithium, nitrogen). Because of their high reactivity, they must be stored under oil to prevent reaction with air, and are found naturally only in salts and never as the free elements. Caesium, the fifth alkali metal, is the most reactive of all the metals. All the alkali metals react with water, with the heavier alkali metals reacting more vigorously than the lighter ones.

Caesium (IUPAC spelling; also spelled cesium in American English) is a chemical element; it has symbol Cs and atomic number 55. It is a soft, silvery-golden alkali metal with a melting point of 28.5 °C (83.3 °F; 301.6 K), which makes it one of only five elemental metals that are liquid at or near room temperature. Caesium has physical and chemical properties similar to those of rubidium and potassium. It is pyrophoric and reacts with water even at −116 °C (−177 °F). It is the least electronegative stable element, with a value of 0.79 on the Pauling scale. It has only one stable isotope, caesium-133. Caesium is mined mostly from pollucite. Caesium-137, a fission product, is extracted from waste produced by nuclear reactors. It has the largest atomic radius of all elements whose radii have been measured or calculated, at about 260 picometres.

The German chemist Robert Bunsen and physicist Gustav Kirchhoff discovered caesium in 1860 by the newly developed method of flame spectroscopy. The first small-scale applications for caesium were as a "getter" in vacuum tubes and in the light-sensitive anodes of photoelectric cells. Caesium is widely used in highly accurate atomic clocks. In 1967, the International System of Units began using a specific hyperfine transition of neutral caesium-133 atoms to define the basic unit of time, the second.

Alkali metal nitrates are chemical compounds consisting of an alkali metal (lithium, sodium, potassium, rubidium and caesium) and the nitrate ion. Only two are of major commercial value, the sodium and potassium salts. They are white, water-soluble salts with melting points ranging from 255 °C (LiNO
₃) to 414 °C (CsNO
₃) on a relatively narrow span of 159 °C

The melting point of the alkali metal nitrates tends to increase from 255 °C to 414 °C (with an anomaly for rubidium being not properly aligned in the series) as the atomic mass and the ionic radius (naked cation) of the alkaline metal increases, going down in the column. Similarly, but not presented here in the table, the solubility of these salts in water also decreases with the atomic mass of the metal.

A liquid metal is a metal or a metal alloy which is liquid at or near room temperature.

The only stable liquid elemental metal at room temperature is mercury (Hg), which is molten above −38.8 °C (234.3 K, −37.9 °F). Three more stable elemental metals melt just above room temperature: caesium (Cs), which has a melting point of 28.5 °C (83.3 °F); gallium (Ga) (30 °C [86 °F]); and rubidium (Rb) (39 °C [102 °F]). The radioactive metal francium (Fr) is probably liquid close to room temperature as well. Calculations predict that the radioactive metals copernicium (Cn) and flerovium (Fl) should also be liquid at room temperature.

Pollucite is a zeolite mineral with the formula (Cs,Na)₂Al₂Si₄O₁₂·2H₂O with iron, calcium, rubidium and potassium as common substituting elements. It is important as a significant ore of caesium and sometimes rubidium. It forms a solid solution series with analcime. It crystallizes in the isometric-hexoctahedral crystal system as colorless, white, gray, or rarely pink and blue masses. Well-formed crystals are rare. It has a Mohs hardness of 6.5 and a specific gravity of 2.9, with a brittle fracture and no cleavage.

Robert Wilhelm Eberhard Bunsen (German: [ˈʁoːbɛʁt ˈbʊnzn̩]; 30 March 1811– 16 August 1899) was a German chemist. He investigated emission spectra of heated elements, and discovered caesium in 1860 and rubidium in 1861 with the physicist Gustav Kirchhoff. The Bunsen–Kirchhoff Award for spectroscopy is named after Bunsen and Kirchhoff.

Bunsen also developed several gas-analytical methods, was a pioneer in photochemistry, and did early work in the field of organic arsenic chemistry. With his laboratory assistant Peter Desaga, he developed the Bunsen burner, an improvement on the laboratory burners then in use.

A mononuclidic element or monotopic element is one of the 21 chemical elements that is found naturally on Earth essentially as a single nuclide (which may, or may not, be a stable nuclide). This single nuclide will have a characteristic atomic mass. Thus, the element's natural isotopic abundance is dominated by one isotope that is either stable or very long-lived. There are 19 elements in the first category (which are both monoisotopic and mononuclidic), and 2 (bismuth and protactinium) in the second category (mononuclidic but not monoisotopic, since they have zero, not one, stable nuclides). A list of the 21 mononuclidic elements is given at the end of this article.

Of the 26 monoisotopic elements that, by definition, have only one stable isotope, seven are not considered mononuclidic, due to the presence of a significant fraction of a very long-lived (primordial) radioisotope. These elements are vanadium, rubidium, indium, lanthanum, europium, lutetium, and rhenium.

Rubidium sesquioxide is a chemical compound with the formula Rb₂O₃ or more accurately Rb₄O₆. In terms of oxidation states, Rubidium in this compound has a nominal charge of +1, and the oxygen is a mixed peroxide (O2−2) and superoxide (O−2) for a structural formula of (Rb)₄(O−2)₂(O2−2). It has been studied theoretically as an example of a strongly correlated material.

The compound was predicted to be a rare example of a ferromagnetic compound that is magnetic due to a p-block element, and a half-metal that was conducting in the minority spin band. However, while the material does have exotic magnetic behavior, experimental results instead showed an electrically insulating magnetically frustrated system. Rb₄O₆ also displays a Verwey transition where charge ordering appears at 290 K.

Lepidolite is the common name for a lilac-gray or rose-colored series of minerals in the mica group. The mineralogical name for this series is the polylithionite-trilithionite series. Lepidolite has a chemical formula of K(Li,Al)₃(Al,Si)₄O₁₀(F,OH)₂. It is the most abundant lithium-bearing mineral and is a secondary source of this metal. It is also the major source of the alkali metal rubidium, which substitutes (as in all minerals) for potassium.

Lepidolite is found with other lithium-bearing minerals, such as spodumene, in pegmatite bodies. It has also been found in high-temperature quartz veins, greisens and granite.

A period 5 element is one of the chemical elements in the fifth row (or period) of the periodic table of the chemical elements. The periodic table is laid out in rows to illustrate recurring (periodic) trends in the chemical behaviour of the elements as their atomic number increases: a new row is begun when chemical behaviour begins to repeat, meaning that elements with similar behaviour fall into the same vertical columns. The fifth period contains 18 elements, beginning with rubidium and ending with xenon. As a rule, period 5 elements fill their 5s shells first, then their 4d, and 5p shells, in that order; however, there are exceptions, such as rhodium.

Quantum information is the information of the state of a quantum system. It is the basic entity of study in quantum information science, and can be manipulated using quantum information processing techniques. Quantum information refers to both the technical definition in terms of von Neumann entropy and the general computational term.

It is an interdisciplinary field that involves quantum mechanics, computer science, information theory, philosophy and cryptography among other fields. Its study is also relevant to disciplines such as cognitive science, psychology and neuroscience. Its main focus is in extracting information from matter at the microscopic scale. Observation in science is one of the most important ways of acquiring information and measurement is required in order to quantify the observation, making this crucial to the scientific method. In quantum mechanics, due to the uncertainty principle, non-commuting observables cannot be precisely measured simultaneously, as an eigenstate in one basis is not an eigenstate in the other basis. According to the eigenstate–eigenvalue link, an observable is well-defined (definite) when the state of the system is an eigenstate of the observable. Since any two non-commuting observables are not simultaneously well-defined, a quantum state can never contain definitive information about both non-commuting observables.

The Zeeman effect (Dutch: [ˈzeːmɑn]) is the splitting of a spectral line into several components in the presence of a static magnetic field. It is caused by the interaction of the magnetic field with the magnetic moment of the atomic electron associated with its orbital motion and spin; this interaction shifts some orbital energies more than others, resulting in the split spectrum. The effect is named after the Dutch physicist Pieter Zeeman, who discovered it in 1896 and received a Nobel Prize in Physics for this discovery. It is analogous to the Stark effect, the splitting of a spectral line into several components in the presence of an electric field. Also, similar to the Stark effect, transitions between different components have, in general, different intensities, with some being entirely forbidden (in the dipole approximation), as governed by the selection rules.

Since the distance between the Zeeman sub-levels is a function of magnetic field strength, this effect can be used to measure magnetic field strength, e.g. that of the Sun and other stars or in laboratory plasmas.