Search results
Results From The WOW.Com Content Network
Caesium (IUPAC spelling; [9] 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.
A chemical element, often simply called an element, is a type of atom which has a specific number of protons in its atomic nucleus (i.e., a specific atomic number, or Z). [ 1 ] The definitive visualisation of all 118 elements is the periodic table of the elements , whose history along the principles of the periodic law was one of the founding ...
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.
Caesium or cesium [note 1] is the chemical element with the symbol Cs and atomic number 55. It is a soft, silvery-gold alkali metal with a melting point of 28 °C (82 °F), which makes it one of only five elemental metals that are liquid at (or near) room temperature.
The overlaps get quite close at the point where the d-orbitals enter the picture, [50] and the order can shift slightly with atomic number [51] and atomic charge. [52] [h] Starting from the simplest atom, this lets us build up the periodic table one at a time in order of atomic number, by considering the cases of single atoms.
A caesium atomic fountain used as part of an atomic clock. ... Δν Cs, of exactly 9 192 631 ... this number was 0.012 × the mass ratio between the IPK and a carbon ...
Caesium (55 Cs) has 41 known isotopes, the atomic masses of these isotopes range from 112 to 152. Only one isotope, 133 Cs, is stable. The longest-lived radioisotopes are 135 Cs with a half-life of 1.33 million years, 137 Cs with a half-life of 30.1671 years and 134 Cs with a half-life of 2.0652 years. All other isotopes have half-lives less ...
The atomic number is redundant to the chemical element, but is sometimes used to emphasize the change of numbers of nucleons in a nuclear reaction. If necessary, a state of ionization or an excited state may be indicated in the right superscript position (e.g., state of ionization Ca 2+ ).