Silicon Silicon is a chemical element; it has symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic lustre, and is a tetravalent metalloid (sometimes considered a non-metal) and semiconductor. It is a membe ...

(₁₄Si) has 25 known

isotope Isotopes are distinct nuclear species (or ''nuclides'') of the same chemical element. They have the same atomic number (number of protons in their Atomic nucleus, nuclei) and position in the periodic table (and hence belong to the same chemica ...

s, with

mass number The mass number (symbol ''A'', from the German word: ''Atomgewicht'', "atomic weight"), also called atomic mass number or nucleon number, is the total number of protons and neutrons (together known as nucleons) in an atomic nucleus. It is appro ...

s ranging from 22 to 46. ²⁸Si (the most abundant isotope, at 92.23%), ²⁹Si (4.67%), and ³⁰Si (3.1%) are stable. The longest-lived radioisotope is ³²Si, which is produced by

cosmic ray spallation Cosmic ray spallation, also known as the x-process, is a set of naturally occurring nuclear reactions causing nucleosynthesis; it refers to the formation of chemical elements from the impact of cosmic rays on an object. Cosmic rays are highly ene ...

argon Argon is a chemical element; it has symbol Ar and atomic number 18. It is in group 18 of the periodic table and is a noble gas. Argon is the third most abundant gas in Earth's atmosphere, at 0.934% (9340 ppmv). It is more than twice as abu ...

. Its

half-life Half-life is a mathematical and scientific description of exponential or gradual decay. Half-life, half life or halflife may also refer to: Film * Half-Life (film), ''Half-Life'' (film), a 2008 independent film by Jennifer Phang * ''Half Life: ...

has been determined to be approximately 150 years (with

decay energy The decay energy is the energy change of a nucleus having undergone a radioactive decay. Radioactive decay is the process in which an unstable atomic nucleus loses energy by emitting ionizing particles and radiation. This decay, or loss of energ ...

0.21 MeV), and it decays by

beta emission In nuclear physics, beta decay (β-decay) is a type of radioactive decay in which an atomic nucleus emits a beta particle (fast energetic electron or positron), transforming into an isobar of that nuclide. For example, beta decay of a neutron t ...

to ³² P (which has a 14.27-day half-life) and then to ³² S. After ³²Si, ³¹Si has the second longest half-life at 157.3 minutes. All others have half-lives under 7 seconds. Isotopes_of_Silicon

List of isotopes

, -id=Silicon-22 , rowspan=3, ²²Si , rowspan=3 style="text-align:right" , 14 , rowspan=3 style="text-align:right" , 8 , rowspan=3, 22.03611(54)# , rowspan=3, 28.7(11) ms , β⁺, p (62%) , ²¹Mg , rowspan=3, 0+ , rowspan=3, , rowspan=3, , - , β⁺ (37%) , ²²Al , - , β⁺, 2p (0.7%) , ²⁰Na , -id=Silicon-23 , rowspan=3, ²³Si , rowspan=3 style="text-align:right" , 14 , rowspan=3 style="text-align:right" , 9 , rowspan=3, 23.02571(54)# , rowspan=3, 42.3(4) ms , β⁺, p (88%) , ²²Mg , rowspan=3, 3/2+# , rowspan=3, , rowspan=3, , - , β⁺ (8%) , ²³Al , - , β⁺, 2p (3.6%) , ²¹Na , -id=Silicon-24 , rowspan=2, ²⁴Si , rowspan=2 style="text-align:right" , 14 , rowspan=2 style="text-align:right" , 10 , rowspan=2, 24.011535(21) , rowspan=2, 143.2 (21) ms , β⁺ (65.5%) , ²⁴Al , rowspan=2, 0+ , rowspan=2, , rowspan=2, , - , β⁺, p (34.5%) , ²³Mg , -id=Silicon-25 , rowspan=2, ²⁵Si , rowspan=2 style="text-align:right" , 14 , rowspan=2 style="text-align:right" , 11 , rowspan=2, 25.004109(11) , rowspan=2, 220.6(10) ms , β⁺ (65%) , ²⁵Al , rowspan=2, 5/2+ , rowspan=2, , rowspan=2, , - , β⁺, p (35%) , ²⁴Mg , -id=Silicon-26 , ²⁶Si , style="text-align:right" , 14 , style="text-align:right" , 12 , 25.99233382(12) , 2.2453(7) s , β⁺ , ²⁶Al , 0+ , , , -id=Silicon-27 , ²⁷Si , style="text-align:right" , 14 , style="text-align:right" , 13 , 26.98670469(12) , 4.117(14) s , β⁺ , ²⁷Al , 5/2+ , , , - , ²⁸Si , style="text-align:right" , 14 , style="text-align:right" , 14 , 27.97692653442(55) , colspan=3 align=center, Stable , 0+ , 0.92223(19) , 0.92205–0.92241 , - , ²⁹Si , style="text-align:right" , 14 , style="text-align:right" , 15 , 28.97649466434(60) , colspan=3 align=center, Stable , 1/2+ , 0.04685(8) , 0.04678–0.04692 , -id=Silicon-30 , ³⁰Si , style="text-align:right" , 14 , style="text-align:right" , 16 , 29.973770137(23) , colspan=3 align=center, Stable , 0+ , 0.03092(11) , 0.03082–0.03102 , -id=Silicon-31 , ³¹Si , style="text-align:right" , 14 , style="text-align:right" , 17 , 30.975363196(46) , 157.16(20) min , β⁻ , ³¹P , 3/2+ , , , -id=Silicon-32 , ³²Si , style="text-align:right" , 14 , style="text-align:right" , 18 , 31.97415154(32) , 157(7) y , β⁻ , ³²P , 0+ ,

trace Trace may refer to: Arts and entertainment Music * ''Trace'' (Son Volt album), 1995 * ''Trace'' (Died Pretty album), 1993 * Trace (band), a Dutch progressive rock band * ''The Trace'' (album), by Nell Other uses in arts and entertainment * ...

cosmogenic Cosmogenic nuclides (or cosmogenic isotopes) are rare nuclides (isotopes) created when a high-energy cosmic ray interacts with the nucleus of an ''in situ'' Solar System atom, causing nucleons (protons and neutrons) to be expelled from the atom ( ...

, -id=Silicon-33 , ³³Si , style="text-align:right" , 14 , style="text-align:right" , 19 , 32.97797696(75) , 6.18(18) s , β⁻ , ³³P , 3/2+ , , , - , ³⁴Si , style="text-align:right" , 14 , style="text-align:right" , 20 , 33.97853805(86) , 2.77(20) s , β⁻ , ³⁴P , 0+ , , , -id=Silicon-34m , style="text-indent:1em" , ^34mSi , colspan=3 style="text-indent:2em" , 4256.1(4) keV , <210 ns , IT , ³⁴Si , (3−) , , , -id=Silicon-35 , rowspan=2, ³⁵Si , rowspan=2 style="text-align:right" , 14 , rowspan=2 style="text-align:right" , 21 , rowspan=2, 34.984550(38) , rowspan=2, 780(120) ms , β⁻ , ³⁵P , rowspan=2, 7/2−# , rowspan=2, , rowspan=2, , - , β⁻, n? , ³⁴P , -id=Silicon-36 , rowspan=2, ³⁶Si , rowspan=2 style="text-align:right" , 14 , rowspan=2 style="text-align:right" , 22 , rowspan=2, 35.986649(77) , rowspan=2, 503(2) ms , β⁻ (88%) , ³⁶P , rowspan=2, 0+ , rowspan=2, , rowspan=2, , - , β⁻, n (12%) , ³⁵P , -id=Silicon-37 , rowspan=3, ³⁷Si , rowspan=3 style="text-align:right" , 14 , rowspan=3 style="text-align:right" , 23 , rowspan=3, 36.99295(12) , rowspan=3, 141.0(35) ms , β⁻ (83%) , ³⁷P , rowspan=3, (5/2−) , rowspan=3, , rowspan=3, , - , β⁻, n (17%) , ³⁶P , - , β⁻, 2n? , ³⁵P , -id=Silicon-38 , rowspan=2, ³⁸Si , rowspan=2 style="text-align:right" , 14 , rowspan=2 style="text-align:right" , 24 , rowspan=2, 37.99552(11) , rowspan=2, 63(8) ms , β⁻ (75%) , ³⁸P , rowspan=2, 0+ , rowspan=2, , rowspan=2, , - , β⁻, n (25%) , ³⁷P , -id=Silicon-39 , rowspan=3, ³⁹Si , rowspan=3 style="text-align:right" , 14 , rowspan=3 style="text-align:right" , 25 , rowspan=3, 39.00249(15) , rowspan=3, 41.2(41) ms , β⁻ (67%) , ³⁹P , rowspan=3, (5/2−) , rowspan=3, , rowspan=3, , - , β⁻, n (33%) , ³⁸P , - , β⁻, 2n? , ³⁷P , -id=Silicon-40 , rowspan=3, ⁴⁰Si , rowspan=3 style="text-align:right" , 14 , rowspan=3 style="text-align:right" , 26 , rowspan=3, 40.00608(13) , rowspan=3, 31.2(26) ms , β⁻ (62%) , ⁴⁰P , rowspan=3, 0+ , rowspan=3, , rowspan=3, , - , β⁻, n (38%) , ³⁹P , - , β⁻, 2n? , ³⁸P , -id=Silicon-41 , rowspan=3, ⁴¹Si , rowspan=3 style="text-align:right" , 14 , rowspan=3 style="text-align:right" , 27 , rowspan=3, 41.01417(32)# , rowspan=3, 20.0(25) ms , β⁻, n (>55%) , ⁴⁰P , rowspan=3, 7/2−# , rowspan=3, , rowspan=3, , - , β⁻ (<45%) , ⁴¹P , - , β⁻, 2n? , ³⁹P , -id=Silicon-42 , rowspan=3, ⁴²Si , rowspan=3 style="text-align:right" , 14 , rowspan=3 style="text-align:right" , 28 , rowspan=3, 42.01808(32)# , rowspan=3, 15.5(4 ( stat), 16 ( sys)) ms , β⁻ (51%) , ⁴²P , rowspan=3, 0+ , rowspan=3, , rowspan=3, , - , β⁻, n (48%) , ⁴¹P , - , β⁻, 2n (1%) , ⁴⁰P , -id=Silicon-43 , rowspan=3, ⁴³Si , rowspan=3 style="text-align:right" , 14 , rowspan=3 style="text-align:right" , 29 , rowspan=3, 43.02612(43)# , rowspan=3, 13(4 ( stat), 2 ( sys)) ms , β⁻, n (52%) , ⁴²P , rowspan=3, 3/2−# , rowspan=3, , rowspan=3, , - , β⁻ (27%) , ⁴³P , - , β⁻, 2n (21%) , ⁴¹P , -id=Silicon-44 , rowspan=3, ⁴⁴Si , rowspan=3 style="text-align:right" , 14 , rowspan=3 style="text-align:right" , 30 , rowspan=3, 44.03147(54)# , rowspan=3, 4# ms 360 ns, β⁻? , ⁴⁴P , rowspan=3, 0+ , rowspan=3, , rowspan=3, , - , β⁻, n? , ⁴³P , - , β⁻, 2n? , ⁴²P , -id=Silicon-45 , ⁴⁵Si , style="text-align:right" , 14 , style="text-align:right" , 31 , 45.03982(64)# , 4# ms , , , 3/2−# , , , -id=Silicon-46 , ⁴⁶Si , style="text-align:right" , 14 , style="text-align:right" , 32 , , , , , , ,

Silicon-28

Silicon-28, the most abundant isotope of silicon, is of particular interest in the construction of

quantum computers A quantum computer is a computer that exploits quantum mechanical phenomena. On small scales, physical matter exhibits properties of both particles and waves, and quantum computing takes advantage of this behavior using specialized hardware. C ...

when highly enriched, as the presence of ²⁹Si in a sample of silicon contributes to

quantum decoherence Quantum decoherence is the loss of quantum coherence. It involves generally a loss of information of a system to its environment. Quantum decoherence has been studied to understand how quantum systems convert to systems that can be expla ...

. Extremely pure (>99.9998%) samples of ²⁸Si can be produced through selective

ionization Ionization or ionisation is the process by which an atom or a molecule acquires a negative or positive Electric charge, charge by gaining or losing electrons, often in conjunction with other chemical changes. The resulting electrically charged at ...

and deposition of ²⁸Si from

silane Silane (Silicane) is an inorganic compound with chemical formula . It is a colorless, pyrophoric gas with a sharp, repulsive, pungent smell, somewhat similar to that of acetic acid. Silane is of practical interest as a precursor to elemental ...

gas. Due to the extremely high purity that can be obtained in this manner, the

Avogadro project The scientific community examined several approaches to redefining the kilogram before deciding on a revision of the SI in November 2018. Each approach had advantages and disadvantages. Prior to the redefinition, the kilogram and several other ...

sought to develop a new definition of the

kilogram The kilogram (also spelled kilogramme) is the base unit of mass in the International System of Units (SI), equal to one thousand grams. It has the unit symbol kg. The word "kilogram" is formed from the combination of the metric prefix kilo- (m ...

by making a sphere of the isotope and determining the exact number of atoms in the sample. Silicon-28 is produced in stars during the

alpha process The alpha process, also known as alpha capture or the alpha ladder, is one of two classes of nuclear fusion reactions by which stars convert helium into heavier elements. The other class is a cycle of reactions called the triple-alpha process, w ...

and the

oxygen-burning process The oxygen-burning process is a set of nuclear fusion reactions that take place in massive stars that have used up the lighter elements in their cores. Oxygen-burning is preceded by the neon-burning process and succeeded by the silicon-burning p ...

, and drives the

silicon-burning process In astrophysics, silicon burning is a very brief sequence of nuclear fusion reactions that occur in massive stars with a minimum of about 8–11 solar masses. Silicon burning is the final stage of fusion for massive stars that have run out of the f ...

in massive stars shortly before they go

supernova A supernova (: supernovae or supernovas) is a powerful and luminous explosion of a star. A supernova occurs during the last stellar evolution, evolutionary stages of a massive star, or when a white dwarf is triggered into runaway nuclear fusion ...

Silicon-29

Silicon-29 is of note as the only stable silicon isotope with a nonzero

nuclear spin Nuclear may refer to: Physics Relating to the nucleus of the atom: * Nuclear engineering * Nuclear physics * Nuclear power * Nuclear reactor * Nuclear weapon * Nuclear medicine *Radiation therapy *Nuclear warfare Mathematics * Nuclear space * ...

(''I'' = 1/2). As such, it can be employed in

nuclear magnetic resonance Nuclear magnetic resonance (NMR) is a physical phenomenon in which nuclei in a strong constant magnetic field are disturbed by a weak oscillating magnetic field (in the near field) and respond by producing an electromagnetic signal with a ...

and hyperfine transition studies, for example to study the properties of the so-called A-center defect in pure silicon.

Silicon-34

Silicon-34 is a radioactive isotope with a half-life of 2.8 seconds. In addition to the usual ''N'' = 20 closed shell, the nucleus also shows a strong ''Z'' = 14 shell closure, making it behave like a doubly magic spherical nucleus, except that it is also located two protons above an island of inversion. Silicon-34 has an unusual "bubble" structure where the proton distribution is less dense at the center than near the surface, as the 2''s''_1/2 proton orbital is almost unoccupied in the ground state, unlike in ³⁶S where it is almost full. Silicon-34 is one of the known

cluster decay Cluster decay, also named heavy particle radioactivity, heavy ion radioactivity or heavy cluster decay," is a rare type of nuclear decay in which an atomic nucleus emits a small "cluster" of neutrons and protons, more than in an alpha particle, ...

emission particles; it is produced in the decay of ²⁴²Cm with a branching ratio of approximately .

References

External links