Search results
Results From The WOW.Com Content Network
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.
In chemistry and atomic physics, an electron shell may be thought of as an orbit that electrons follow around an atom's nucleus.The closest shell to the nucleus is called the "1 shell" (also called the "K shell"), followed by the "2 shell" (or "L shell"), then the "3 shell" (or "M shell"), and so on further and further from the nucleus.
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.
This notation is used to specify electron configurations and to create the term symbol for the electron states in a multi-electron atom. When writing a term symbol, the above scheme for a single electron's orbital quantum number is applied to the total orbital angular momentum associated to an electron state. [4]
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 ...
For atoms, the notation consists of a sequence of atomic subshell labels (e.g. for phosphorus the sequence 1s, 2s, 2p, 3s, 3p) with the number of electrons assigned to each subshell placed as a superscript. For example, hydrogen has one electron in the s-orbital of the first shell, so its configuration is written 1s 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.
The 2s subshell is completed by the next element beryllium (1s 2 2s 2). The following elements then proceed to fill the 2p subshell. Boron (1s 2 2s 2 2p 1) puts its new electron in a 2p orbital; carbon (1s 2 2s 2 2p 2) fills a second 2p orbital; and with nitrogen (1s 2 2s 2 2p 3) all three 2p orbitals become singly occupied.