proton

[zhì z ǐ]

Subatomic particle

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Proton is a kind of -19 Coulomb (C) positive charge Of Subatomic particle , diameter about 1.6~1.7 × 10 −15 m. The quality is 938 million Electron volt /c ² (MeV/c ²)， Namely 1.672621637 (83) × 10 -27 Kg, about 1836.5 times the electronic mass（ Electronics The mass of 9.10938215 (45) × 10 -31 Kg), proton is slightly lighter than neutron（ neutron The mass of is 1.674927211 (84) × 10 -27 Kg). Protons belong to baryon Class, consisting of two Upper quark And a Lower quark adopt Gluon stay Strong interaction Below. Nucleus The number of protons in element What kind of chemical element 。^[1]

Chinese name: proton
Foreign name: proton
Particle type: Composite particle

Discipline: Physics
Discovery time: 1918
Discoverer: Ernest Rutherford

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nine Proton conservation
ten scientific research

Basic properties

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Relative mass: one point zero zero seven

Charge: +1-element charge (+1.602176634 × 10 -19 Coulomb ）

Particle spin ： 1/2

Particle magnetic moment: 2.7928 unit NMR

Force: gravitation , electromagnetic force Weak nuclear force Strong nuclear force

half life ： Minimum 10 thirty-five Year (considered stable)

form: Two Upper quark , one Lower quark

Proton number=atomic number (i.e. element number)=number of extranuclear electrons, neutron number=mass number - proton number

1. The oxygen element is the element of the second cycle, so the oxygen atom has only two electrons, two from the inner layer and six from the outer layer, a total of eight electrons; The number of protons of oxygen atom is also 8. The number of extranuclear electrons=the number of protons, so the oxygen atom itself is electrically neutral and has no charge.

In fact, all atoms are electrically neutral and conform to [proton number]=[atomic number]=[nuclear charge number]=[extranuclear electron number]

2. The number of extranuclear electrons of the atom in each substance must be equal to the number of protons of the atom, but this does not mean that this structure is stable, it is just a characteristic of element atoms. For example, the Na atom is very unstable. It is easy to lose an electron and become Na+, with a positive charge, to reach a stable structure. Note that the charge is due to the ion. For Na atoms that have not lost electrons, the number of extranuclear electrons=the number of protons

Encyclopedia x Knowledgeable: Illustration of Particles

history

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Proton linac

britain physical scientist Ernest Rutherford Is recognized as the discoverer of protons. He was appointed in 1918 Cavendish Laboratory When director, use α particle Bombard nitrogen Nucleus , note that in the use of α particle bombardment nitrogen His flash detector recorded signs of hydrogen nuclei. Proton is named proton, and this word is Greece The "first" in the article evolved. Rutherford realized that the only possible source of these hydrogen nuclei was nitrogen atoms, so nitrogen atoms must contain hydrogen nuclei. He therefore suggested Atomic number The hydrogen nucleus of 1 is a Elementary particle 。 Before that, Eugene Goldstein had noticed that anode rays were generated by Positive ion Composed of. But he failed to analyze these Ions Components of. After Rutherford discovered the proton, he predicted the existence of neutral neutrons.

Today Particle physics Of Standard Model Theory As the proton is Composite particle , so it is no longer included in the family of elementary particles.

On March 25, 2024, according to the official website of the European Center for Nuclear Research (CERN), the International Cooperation Group of the Compact Muon Coil (CMS) on the Large Hadron Collider (LHC) announced that they used the excellent tracking ability of the CMS track detector to observe for the first time that two photons were "transformed" into two pottery particles in the proton collision（ τ）。^[3]

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Rutherford did it in 1919 α For the experiment of particle bombarding nitrogen nucleus, the experimental device is as shown in the figure. The container C contains radioactive material A, which is ejected from A α The particles shoot onto the aluminum foil F, select the thickness of the aluminum foil properly, and vacuum the container C, α The particles are just absorbed by F and cannot be penetrated. Put a fluorescent screen S behind F, and use the microscope book to observe whether there is flash on the fluorescent screen. After nitrogen is introduced into C through the valve T, Rutherford observed the flash on the fluorescent screen S, and changed nitrogen into oxygen or carbon dioxide, but no flash was observed, which indicates that the flash must be α The new particles generated after the particles hit the nitrogen core are caused through the aluminum foil.

Rutherford introduced this particle into the electric and magnetic fields. According to its deflection in the electric and magnetic fields, he measured its mass and electric quantity, and determined that it was a hydrogen nucleus, also called a proton, usually with the symbol one H or p means.

This proton is α The particles are directly shot from the nitrogen core, or α What about the particles released when the recheck formed after entering the recheck decays? In order to understand this problem, British physicist Brakate did this experiment again in a nitrogen filled cloud chamber. If the proton is α The particles are shot directly from the nitrogen nucleus, and then four tracks can be seen in the cloud chamber: radiation α Track of particles, scattering after collision. The track of particles, the track of protons and the recoil track of the nucleus after throwing protons. If the particles enter the nitrogen nucleus and form a recheck, which immediately decays and releases a proton, then three tracks can be seen in the cloud chamber: incidence α The tracks of particles, protons and recoil nuclei. Brakate took more than 20000 photos of the cloud chamber, and finally found that eight of the more than 400000 photos of "particle tracks" had bifurcated. The bifurcations showed that the second assumption was correct. From the conservation of mass number and charge number, we can know that the new nucleus produced was oxygen 17.

In the picture of the cloud chamber, after the bifurcation, the thin and long tracks are proton tracks, and the short and thick tracks are recoil oxygen nuclei.

Later, people used the same method to make fluorine, sodium, aluminum and other nuclei undergo similar transformations, and all produced protons. Since protons can be bombarded from all kinds of nuclei, it can be seen that protons are part of atomic nuclei.

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In physics, protons are often used in accelerator It is used to collide with other particles after accelerating to near light speed. Such tests are for research Nucleus Structure provides extremely important data. Slow protons may also be absorbed by atomic nuclei to make artificial isotopes or Artificial element 。 Nuclear magnetic resonance Resonance technique Protonic spin To test the molecular structure.

steady-state

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So far, protons are considered to be stable decay The particles of. But there are also theories that protons may decay , but its life is very long. Until today physical scientist Not able to obtain any possible understanding Proton decay Experimental data. The measured proton lifetime is more than 10 thirty-five Years.

Most hydrogen ions in water are hydrated protons. Protons play a very important role in chemistry and biochemistry according to Acid base proton theory The substance that can provide protons in aqueous solution is generally called acid, and the substance that can absorb protons in aqueous solution is generally called alkali.

However, protons are trapped by electrons in the process of neutrons. This process will not happen spontaneously, but only when energy is supplied. Its calculation formula:

Here

P is a proton,

Shell structure diagram of mercury atom

E is a Electronics ，

N is a neutron , and

ν E is an electron neutrino

This process is reversible: neutrons can be converted back to protons through β- decay , jointly formed Radioactive decay 。 In fact, in a free neutron decay such an average lifetime is about 15 minutes.

Antiproton

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The antiparticle of the proton is Antiproton , the antiproton was created in 1955 by Emilio Gino Segr è and Owen Chamberlain (Owen Chamberlain), for which they obtained the The nobel prize in physics 。

Proton magnetometer

Discovery of antiprotons: positron The discovery of Theoretical physicist We began to take this theory seriously. In 1934, Pauli and Kraft proved that even if a stable negative energy particle sea could not be formed, there would be corresponding antiparticles. So people began to look for antiparticles of other particles. As early as 1928, Dirac predicted the existence of antiproton, but it took more than 20 years to confirm its existence. According to Dirac's theory, the antiproton has the same mass as the proton charge On the contrary, protons and antiprotons appear or annihilate in pairs, and antiprotons can be obtained by colliding two ordinary protons, but the threshold energy of antiprotons is 6.8 GeV. In 1954 University Of California Of Lawrence Radiation Laboratory A 6.4 billion electron volt proton synchronous phase stabilized accelerator has been built, which provides conditions for searching for antiparticles. In 1955, Chamberlain and Segre The previous

Nuclear weapon atomic bomb

The existence of antiprotons observed in. Since antiprotons have very few opportunities, only a small number of antiprotons can be generated every 100 billion high-energy proton collisions, so it is extremely difficult to confirm the existence of antiprotons. In 1955, their experimental group measured 60 antiprotons. Because the background of accidental coincidence is not large, the numeration system is not good, but it is more reliable. Soon they found out Antineutron 。 although High-energy particle Antineutrons can also be generated when shooting, but because the antineutron is not charged, it is more difficult to identify it from other particles. They use antiprotons to collide with atomic nuclei, and antiprotons negative charge Give it to the proton, or obtain a positive charge from the proton, so that the proton becomes a neutron, and the antiproton becomes an antineutron. Rubia, C. on the pros and cons proton collider The collision experiment of several hundred gigaton volts on the Unified theory of weak electricity The predicted dynamo, therefore, won the 1984 The nobel prize in physics 。

Symbol p，H +

Discovery time 1919

Discoverer Ernest Rutherford

Formation of neutron state

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Under great pressure, the supersolid matter can no longer tighten the previously crowded atomic nucleus and electrons. At this time, the atomic nucleus has to be dissolved, releasing protons and neutrons from it. The proton emitted from the nucleus will combine with the electron to form a neutron under extreme pressure. In this way, the structure of matter has undergone a fundamental change. The matter originally constructed by atomic nuclei and electrons has now become a neutron. This state is called“ neutron state ”。

Acid base proton theory

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acid-base Ions The theory is that Arrhenius Ionization theory Put forward. He thinks that water Hydrogen production by intermediate energy ionization Ions A substance that does not produce other cations is called acid. Can ionize out in water Hydroxyl ion And does not produce other anions alkali 。 The essence of acid-base neutralization reaction is Hydrogen ion and Hydroxyl ion Combine to form water. This theory has achieved great success, but its limitations have long been exposed. For example, gaseous ammonia reacts with hydrogen chloride to quickly generate ammonium chloride, which is an acid-base neutralization reaction with the generation of water; Another example is that the aqueous solution of ammonia is alkaline, and it was wrongly believed that NH three And H two O formation Weak electrolyte NH four OH molecule, and then dissociate OH - 、NH four + Etc.

because Arenius Of Acid-base ion theory Unable to solve some problems such as the ground acid base reaction in nonaqueous solutions, Bronsted put forward the acid base proton theory in 1923, which popularized the concept of acid base. Acid base proton theory It is believed that all substances that can give protons are acids, and all substances that can combine with protons are bases. That is, acid is the donor of proton, and base is the acceptor of proton. In this way, the remaining part of an acid after giving the proton is naturally the base, because it is bound to the proton itself.

This relationship is called acid-base conjugate relationship, in which the possible charges of HB and B are omitted. The base on the right is the conjugate base of the acid on the left, and the acid on the left is the base on the right Conjugated acid , the two constitute one Conjugated acid base pair They are just one proton away. It can be seen from the above examples that acids and bases can be molecules or cation and anion 。 It can also be seen that, like HPO two -4 Such substances not only represent acid, but also

Proton magnetometer

It behaves as an alkali, so it is an amphoteric substance. Similarly, H two O，HCO three - And so on are also amphoteric substances. II Conjugated acid base Strength of Conjugated acid base pair There is a definite relationship between the dissociation constants Ka and Kb. Taking HOAc as an example, the derivation is as follows: because the concentration of solvent water is not constant, it does not appear in the equilibrium constant Where. Expressed in KW [H three O + ][OH - ], KW is called Ionic product of water 。 This indicates that at a certain temperature, [H three O + ]And [OH - ]The product of is a constant. So K a ·K b =K W (2-7) K at 24 ℃ W The value is 1.0 × 10-14. This relationship shows that only the dissociation constant K of acid is known a K of its conjugate base can be calculated b And vice versa. K a And K b Is inversely proportional, and K a And K b It reflects the strength of acid and alkali. Therefore, when Conjugated acid base pair The stronger the acid is, the weaker the conjugated base is; The stronger the base, the weaker the conjugate acid.

According to the proton theory of acids and bases, the strength of acids and bases in solution is not only related to the nature of acids and bases, but also to the nature of solvents. What we can measure is the relative strength of acid and base in a certain solvent. If the same acid or base is dissolved in different solvents, their relative strength will be different. For example, HOAc is weak acid in water, but liquid ammonia It shows strong acid, because the ability of liquid ammonia to capture protons (i.e. alkalinity) is much stronger than that of water. This phenomenon further explains the relativity of acid-base strength.

3、 Acid-base reaction Acid base proton theory The acid-base reaction in Proton transfer 。 For example, this reaction aqueous solution The substance is the same in the medium, benzene or gas phase. HCl is an acid that emits protons to NH three And then converted to conjugated base Cl - ，NH three It is alkali, which is converted into Conjugated acid NH 4+ 。 The strong base seizes the protons released by the strong acid and converts them into weaker ones Conjugated acid And conjugated bases. The acid-base proton theory not only expands the range of acid-base, but also can dissociate acid-base Neutralization reaction 、 Hydrolysis reaction They are all regarded as proton transfer acid-base reactions. It can be seen that the acid-base proton theory better explains the acid-base reaction, gets rid of the limitation that acid-base reactions can only occur in water, and solves some problems Nonaqueous solvent Or acid-base reaction between gases, and aqueous solution Some ion reactions carried out in are systematically summarized as proton transfer acid-base reactions, which has deepened people's understanding of acid-base and acid-base reactions. But the acid-base proton theory cannot explain those who do not exchange protons but have Acid-base property Of material Therefore, it still has some limitations.

Acids and bases proposed by Louis Electronics The theory is the most generalized acid-base theory at present. According to this theory, if you can Electron pair Of material It is called alkali; Any substance that can accept electron pairs is called acid. That is, acid is Electron pair The base is the donor of the electron pair. Therefore, there is at least one pair of atoms giving electrons in the base Lone pair electron (unbounded Electron pair ）The atom receiving electrons in the acid has at least one empty orbit (the outer layer is not filled with electrons) to accept the electron pairs given by the base. This acid and base defined by Lewis is called Lewis acid and Lewis base 。 For example, boron trifluoride (BF three ）Yes Lewis acid , because BF three B in atom There is an empty track Electronics The acceptor of. NH three There is a pair of N atoms in Lone pair electron Is the donor of the electron pair, Lewis base. However, due to acid-base electrons Theoretical summary The wide range of acid and alkali of the acid and alkali of the acid and alkali of the acid and alkali of the acid and alkali of the acid and alkali of the acid and alkali of the acid and alkali of the acid and alkali of the acid and alkali of the acid and alkali of the acid and alkali of the acid and alkali of the acid and alkali of the acid and alkali of the acid and alkali.

Proton conservation

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Proton conservation means that the number of protons lost by acid is the same as that obtained by base, and the proton conservation and material conservation are the same, Charge conservation Same as the three conservation relations in solution, the proton conservation can also obtain NaHCO from the charge conservation and material conservation three In the solution, the following equation C (H + )+C(Na + )=C(HCO three - )+2C(CO three 2- )+C(OH - ）This formula is called charge conservation C (Na + )=C(HCO three - )+C(CO three 2- )+C(H two CO three ）This formula is called material conservation

Method 1: subtract the two equations to get C (H + ）+C（H two CO three ）=C（CO three 2- ）+C(OH - ）This formula is called proton conservation. Method 2: By Acid base proton theory Original species: HCO three - ，H two O Proton consumption product H two CO three , producing the proton product CO three 2- ，OH-C（H + ）=C（CO three 2- ）+C(OH - )-C（H two CO three ）C (H + ）+C（H two CO three ）=C（CO three 2- ）+C(OH - ）Relationship: The number of remaining protons is equal to the number of products that produce protons - the number of products that consume protons is directly calculated using the acid base proton theory Proton equilibrium The relationship is simple, but careful; If charge conservation and material conservation are used together, it is troublesome, but it is safe, such as NaH two PO four Solution, original species: H two PO 4- ，H two O. Proton consumption product: H three PO four , produce proton product: HPO four 2- (producing a proton), PO four 3- (producing two protons), OH - , so: c (H + ）=c(HPO four 2- )+2c(PO four 3- )+c(OH-)-c（H three PO four ）It can be verified by charge conservation and material conservation simultaneously.

scientific research

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In 2022, American scientists wrote in the latest issue of Nature that, A new accurate measurement of proton polarizability was carried out, and the results showed that the proton structure was abnormal - the proton was more elastic than previously thought, which confirmed the anomaly previously thought to be an error.^[2]

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