Atomic structure of Lithium-7
The chemical elements ordered in the periodic table
Petalite, the lithium mineral from which lithium was first isolated
Lithium ingots with a thin layer of black nitride tarnish
Estimated distribution of dark matter and dark energy in the universe. Only the fraction of the mass and energy in the universe labeled "atoms" is composed of chemical elements.
Johann Wolfgang Döbereiner was among the first to notice similarities between what are now known as the alkali metals.
Lithium floating in oil
Periodic table showing the cosmogenic origin of each element in the Big Bang, or in large or small stars. Small stars can produce certain elements up to sulfur, by the alpha process. Supernovae are needed to produce "heavy" elements (those beyond iron and nickel) rapidly by neutron buildup, in the r-process. Certain large stars slowly produce other elements heavier than iron, in the s-process; these may then be blown into space in the off-gassing of planetary nebulae
Lepidolite, the rubidium mineral from which rubidium was first isolated
Lithium is about as common as chlorine in the Earth's upper continental crust, on a per-atom basis.
Abundances of the chemical elements in the Solar System. Hydrogen and helium are most common, from the Big Bang. The next three elements (Li, Be, B) are rare because they are poorly synthesized in the Big Bang and also in stars. The two general trends in the remaining stellar-produced elements are: (1) an alternation of abundance in elements as they have even or odd atomic numbers (the Oddo-Harkins rule), and (2) a general decrease in abundance as elements become heavier. Iron is especially common because it represents the minimum energy nuclide that can be made by fusion of helium in supernovae.
Dmitri Mendeleev's periodic system proposed in 1871 showing hydrogen and the alkali metals as part of his group I, along with copper, silver, and gold
Nova Centauri 2013 is the first in which evidence of lithium has been found.
Mendeleev's 1869 periodic table: An experiment on a system of elements. Based on their atomic weights and chemical similarities.
Estimated abundances of the chemical elements in the Solar system. Hydrogen and helium are most common, from the Big Bang. The next three elements (lithium, beryllium, and boron) are rare because they are poorly synthesised in the Big Bang and also in stars. The two general trends in the remaining stellar-produced elements are: (1) an alternation of abundance in elements as they have even or odd atomic numbers, and (2) a general decrease in abundance, as elements become heavier. Iron is especially common because it represents the minimum energy nuclide that can be made by fusion of helium in supernovae.
Johan August Arfwedson is credited with the discovery of lithium in 1817
Dmitri Mendeleev
Spodumene, an important lithium mineral
Hexameric structure of the n-butyllithium fragment in a crystal
Henry Moseley
Effective nuclear charge on an atomic electron
Scatter plots of lithium grade and tonnage for selected world deposits, as of 2017
Periodic trend for ionisation energy: each period begins at a minimum for the alkali metals, and ends at a maximum for the noble gases. Predicted values are used for elements beyond 104.
Lithium use in flares and pyrotechnics is due to its rose-red flame.
The variation of Pauling electronegativity (y-axis) as one descends the main groups of the periodic table from the second to the sixth period
The launch of a torpedo using lithium as fuel
A reaction of 3 pounds (≈ 1.4 kg) of sodium with water
Lithium deuteride was used as fuel in the Castle Bravo nuclear device.
Liquid NaK alloy at room temperature
Estimates of global lithium uses in 2011 (picture) and 2019 (numbers below) 
Ceramics and glass (18%)
Batteries (65%)
Lubricating greases (5%)
Continuous casting (3%)
Air treatment (1%)
Polymers
Primary aluminum production
Pharmaceuticals
Other (5%)
Unit cell ball-and-stick model of lithium nitride. On the basis of size a tetrahedral structure would be expected, but that would be geometrically impossible: thus lithium nitride takes on this unique crystal structure.
Structure of the octahedral n-butyllithium hexamer, (C4H9Li)6. The aggregates are held together by delocalised covalent bonds between lithium and the terminal carbon of the butyl chain. There is no direct lithium–lithium bonding in any organolithium compound.
Solid phenyllithium forms monoclinic crystals can be described as consisting of dimeric Li2(C6H5)2 subunits. The lithium atoms and the ipso carbons of the phenyl rings form a planar four-membered ring. The plane of the phenyl groups are perpendicular to the plane of this Li2C2 ring. Additional strong intermolecular bonding occurs between these phenyllithium dimers and the π electrons of the phenyl groups in the adjacent dimers, resulting in an infinite polymeric ladder structure.
Reduction reactions using sodium in liquid ammonia
Empirical (Na–Cs, Mg–Ra) and predicted (Fr–Uhp, Ubn–Uhh) atomic radius of the alkali and alkaline earth metals from the third to the ninth period, measured in angstroms
Empirical (Na–Fr) and predicted (Uue) electron affinity of the alkali metals from the third to the eighth period, measured in electron volts
Empirical (Na–Fr, Mg–Ra) and predicted (Uue–Uhp, Ubn–Uhh) ionisation energy of the alkali and alkaline earth metals from the third to the ninth period, measured in electron volts
Similarly to the alkali metals, ammonia reacts with hydrochloric acid to form the salt ammonium chloride.
Very pure thallium pieces in a glass ampoule, stored under argon gas
This sample of uraninite contains about 100,000 atoms (3.3 g) of francium-223 at any given time.
FOCS 1, a caesium atomic clock in Switzerland
Lithium carbonate
A wheel type radiotherapy device which has a long collimator to focus the radiation into a narrow beam. The caesium-137 chloride radioactive source is the blue square, and gamma rays are represented by the beam emerging from the aperture. This was the radiation source involved in the Goiânia accident, containing about 93 grams of caesium-137 chloride.

Lithium (from λίθος) is a chemical element with the symbol Li and atomic number 3.

- Lithium

The alkali metals consist of the chemical elements lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), and francium (Fr).

- Alkali metal

It is a soft, silvery-white alkali metal.

- Lithium

The lightest chemical elements are hydrogen and helium, both created by Big Bang nucleosynthesis during the first 20 minutes of the universe in a ratio of around 3:1 by mass (or 12:1 by number of atoms), along with tiny traces of the next two elements, lithium and beryllium.

- Chemical element

The version of this classification used in the periodic tables presented here includes: actinides, alkali metals, alkaline earth metals, halogens, lanthanides, transition metals, post-transition metals, metalloids, reactive nonmetals, and noble gases.

- Chemical element
Atomic structure of Lithium-7

5 related topics with Alpha

Overall

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Periodic table

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3D views of some hydrogen-like atomic orbitals showing probability density and phase (g orbitals and higher are not shown)
Idealized order of shell-filling (most accurate for n  ≲ 4.)
Trend in atomic radii
Graph of first ionisation energies of the elements in electronvolts (predictions used for elements 105–118)
Trend in electron affinities
Flowing liquid mercury. Its liquid state at room temperature is a result of special relativity.
A periodic table colour-coded to show some commonly used sets of similar elements. The categories and their boundaries differ somewhat between sources. Alkali metals
 Alkaline earth metals
 Lanthanides
 Actinides
 Transition metals Other metals
 Metalloids
 Other nonmetals
 Halogens
 Noble gases
Mendeleev's 1869 periodic table
Mendeleev's 1871 periodic table
Dmitri Mendeleev
Henry Moseley
Periodic table of van den Broek
Glenn T. Seaborg
One possible form of the extended periodic table to element 172, suggested by Finnish chemist Pekka Pyykkö. Deviations from the Madelung order (8s < < 6f < 7d < 8p) begin to appear at elements 139 and 140, though for the most part it continues to hold approximately.
Otto Theodor Benfey's spiral periodic table (1964)
Iron, a metal
Sulfur, a nonmetal
Arsenic, an element often called a semi-metal or metalloid

The periodic table, also known as the periodic table of the (chemical) elements, is a tabular display of the chemical elements.

Hydrogen is the element with atomic number 1; helium, atomic number 2; lithium, atomic number 3; and so on.

For example, the alkali metals in the first group all have one valence electron, and form a very homogeneous class of elements: they are all soft and reactive metals.

The flame test of potassium.

Potassium

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The flame test of potassium.
Structure of solid potassium superoxide.
Potassium in feldspar
Sir Humphry Davy
Pieces of potassium metal
Sylvite from New Mexico
Monte Kali, a potash mining and beneficiation waste heap in Hesse, Germany, consisting mostly of sodium chloride.
Potassium sulfate/magnesium sulfate fertilizer

Potassium is a chemical element with the symbol K (from Neo-Latin kalium) and atomic number19.

In the periodic table, potassium is one of the alkali metals, all of which have a single valence electron in the outer electron shell, that is easily removed to create an ion with a positive charge – a cation, that combines with anions to form salts.

Potassium is the second least dense metal after lithium.

Emission spectrum for sodium, showing the D line.

Sodium

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Emission spectrum for sodium, showing the D line.
A positive flame test for sodium has a bright yellow color.
The structure of sodium chloride, showing octahedral coordination around Na+ and Cl− centres. This framework disintegrates when dissolved in water and reassembles when the water evaporates.
Two equivalent images of the chemical structure of sodium stearate, a typical soap.
The structure of the complex of sodium (Na+, shown in yellow) and the antibiotic monensin-A.
NaK phase diagram, showing the melting point of sodium as a function of potassium concentration. NaK with 77% potassium is eutectic and has the lowest melting point of the NaK alloys at −12.6 °C.

Sodium is a chemical element with the symbol Na (from Latin natrium) and atomic number 11.

Sodium is an alkali metal, being in group 1 of the periodic table.

Metallic sodium is generally less reactive than potassium and more reactive than lithium.

Atomic orbitals of the electron in a hydrogen atom at different energy levels. The probability of finding the electron is given by the color, as shown in the key at upper right.

Atomic orbital

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Domain coloring of a

Domain coloring of a

Atomic orbitals of the electron in a hydrogen atom at different energy levels. The probability of finding the electron is given by the color, as shown in the key at upper right.
3D views of some hydrogen-like atomic orbitals showing probability density and phase (g orbitals and higher are not shown)
The Rutherford–Bohr model of the hydrogen atom.
Energetic levels and sublevels of polyelectronic atoms.
Experimentally imaged 1s and 2p core-electron orbitals of Sr, including the effects of atomic thermal vibrations and excitation broadening, retrieved from energy dispersive x-ray spectroscopy (EDX) in scanning transmission electron microscopy (STEM).
The 1s, 2s, and 2p orbitals of a sodium atom.
Atomic orbitals spdf m-eigenstates and superpositions
Electron atomic and molecular orbitals. The chart of orbitals (left) is arranged by increasing energy (see Madelung rule). Note that atomic orbits are functions of three variables (two angles, and the distance r from the nucleus). These images are faithful to the angular component of the orbital, but not entirely representative of the orbital as a whole.
Drum mode <math>u_{01}</math>
Drum mode <math>u_{02}</math>
Drum mode <math>u_{03}</math>
Wave function of 1s orbital (real part, 2D-cut, <math>r_{max}=2 a_0</math>)
Wave function of 2s orbital (real part, 2D-cut, <math>r_{max}=10 a_0</math>)
Wave function of 3s orbital (real part, 2D-cut, <math>r_{max}=20 a_0</math>)
Drum mode <math>u_{11}</math>
Drum mode <math>u_{12}</math>
Drum mode <math>u_{13}</math>
Wave function of 2p orbital (real part, 2D-cut, <math>r_{max}=10 a_0</math>)
Wave function of 3p orbital (real part, 2D-cut, <math>r_{max}=20 a_0</math>)
Wave function of 4p orbital (real part, 2D-cut, <math>r_{max}=25 a_0</math>)
Drum mode <math>u_{21}</math>
Drum mode <math>u_{22}</math>
Drum mode <math>u_{23}</math>

They are derived from the description by early spectroscopists of certain series of alkali metal spectroscopic lines as sharp, principal, diffuse, and fundamental.

The repeating periodicity of blocks of 2, 6, 10, and 14 elements within sections of the periodic table arises naturally from the total number of electrons that occupy a complete set of s, p, d, and f orbitals, respectively, though for higher values of quantum number n, particularly when the atom bears a positive charge, the energies of certain sub-shells become very similar and so the order in which they are said to be populated by electrons (e.g., Cr = [Ar]4s13d5 and Cr2+ = [Ar]3d4) can only be rationalized somewhat arbitrarily.

The outermost electrons of Li and Be respectively belong to the 2s subshell, and those of Na and Mg to the 3s subshell.

High-purity caesium-133 stored in argon.

Caesium

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High-purity caesium-133 stored in argon.
Caesium crystals (golden) compared to rubidium crystals (silvery)
Ball-and-stick model of the cubic coordination of Cs and Cl in CsCl
Monatomic caesium halide wires grown inside double-wall carbon nanotubes (TEM image).
cluster
Decay of caesium-137
Pollucite, a caesium mineral
Gustav Kirchhoff (left) and Robert Bunsen (centre) discovered caesium with their newly invented spectroscope.
Atomic clock ensemble at the U.S. Naval Observatory
FOCS-1, a continuous cold caesium fountain atomic clock in Switzerland, started operating in 2004 at an uncertainty of one second in 30 million years
Caesium chloride powder
Schematics of an electrostatic ion thruster developed for use with caesium or mercury fuel
The portion of the total radiation dose (in air) contributed by each isotope plotted against time after the Chernobyl disaster. Caesium-137 became the primary source of radiation about 200 days after the accident.

Caesium (IUPAC spelling ) (or cesium in American English) is a chemical element with the symbol Cs and atomic number 55.

It is a soft, silvery-golden alkali metal with a melting point of 28.5 C, which makes it one of only five elemental metals that are liquid at or near room temperature.

The only economically important ore for caesium is pollucite, which is found in a few places around the world in zoned pegmatites, associated with the more commercially important lithium minerals, lepidolite and petalite.