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Beryllium is a chemical element; it has symbol Be and atomic number 4. It is a steel-gray, hard, strong, lightweight and brittle alkaline earth metal. It is a divalent element that occurs naturally only in combination with other elements to form minerals. Gemstones high in beryllium include beryl (aquamarine, emerald, red beryl) and chrysoberyl.
Beryllium, 4 Be; Beryllium ... {Infobox element/periodic table}} (extends period 8 when atomic number ≥ 119. ... mass number comment: mass number comment: no ...
Beryllium is unique as being the only monoisotopic element with both an even number of protons and an odd number of neutrons. There are 25 other monoisotopic elements but all have odd atomic numbers, and even numbers of neutrons. Of the 10 radioisotopes of beryllium, the most stable are 10 Be with a half-life of 1.387(12) million years [nb 1 ...
Beryllium alloys are used for mechanical parts when stiffness, light weight, and dimensional stability are required over a wide temperature range. [69] [70] Beryllium-9 is used in small-scale neutron sources that use the reaction 9 Be + 4 He (α) → 12 C + 1 n, the reaction used by James Chadwick when he discovered the neutron.
Beryllium (Be) is the chemical element with atomic number 4, occurring in the form of 9 Be. At standard temperature and pressure, beryllium is a strong, steel-grey, light-weight, brittle, bivalent alkaline earth metal, with a density of 1.85 g⋅cm −3. [12] It also has one of the highest melting points of all the light metals.
This is a list of chemical elements and their atomic properties, ordered by atomic number (Z).. Since valence electrons are not clearly defined for the d-block and f-block elements, there not being a clear point at which further ionisation becomes unprofitable, a purely formal definition as number of electrons in the outermost shell has been used.
This page shows the electron configurations of the neutral gaseous atoms in their ground states. For each atom the subshells are given first in concise form, then with all subshells written out, followed by the number of electrons per shell. For phosphorus (element 15) as an example, the concise form is [Ne] 3s 2 3p 3.
Each distinct atomic number therefore corresponds to a class of atom: these classes are called the chemical elements. [5] The chemical elements are what the periodic table classifies and organizes. Hydrogen is the element with atomic number 1; helium, atomic number 2; lithium, atomic number 3; and so on.