Proton and Neutron Combination

Yuánzǐ zhōng suǒyǒu de zhízǐ hé zhōng zǐ jiéhé qǐlái jiù xíngchéngle yīgè hěn xiǎo de yuánzǐhé, tāmen yīqǐ yě kěyǐ bèi chēng wèi hézǐ. Yuánzǐhé de bànjìng yuē děngyú 1.07×A^1/3 fm, qízhōng A shì hézǐ de zǒngshù. Yuánzǐ bànjìng de shùliàngjí dàyuē shì 105fm, yīncǐ yuánzǐhé de bànjìng yuǎn yuǎn xiǎoyú yuánzǐ de bànjìng. Hézǐ bèi néng zài duǎn jùlí shàng qǐ zuòyòng de cánliú qiánglì shùfù zài yīqǐ. Dāng jùlí xiǎoyú 2.5Fm de shíhòu, qiánglì yuǎn yuǎndàyújìng diànlì, yīncǐ tā nénggòu kèfú dài zhèng diàn de zhízǐ jiān de xiānghù páichì. Tóng zhǒng yuánsù de yuánzǐ dài yǒu xiāngtóng shùliàng de zhízǐ, zhège shù yě bèi chēng zuò yuánzǐ xùshù. Ér duìyú mǒu zhǒng tèdìng de yuánsù, zhōng zǐ shù shì kěyǐ biànhuà de, zhè yě jiù juédìngle gāi yuánzǐ shì zhè zhǒng yuánsù de nǎ yī zhǒng tóngwèisù. Zhízǐ shùliàng hé zhōng zǐ shùliàng juédìngle gāi yuánzǐ shì zhè zhǒng yuánsù de nǎ yī zhǒng hé sù. Zhōng zǐ shù juédìngle gāi yuánzǐ de wěndìng chéngdù, yīxiē tóngwèisù nénggòu zìfā jìnxíng fàngshèxìng shuāibiàn. Zhōng zǐ hé zhízǐ dōu shì fèi mǐzi de yī zhǒng, gēnjù liàngzǐ lìxué zhōng de pào lì bù xiāng róng yuánlǐ, bù kěnéng yǒu wánquán xiāngtóng de liǎng gè fèi mǐ zǐ tóngshí yǒngyǒu yīyàng liàngzǐ wùlǐ tài. Yīncǐ, yuánzǐhé zhōng de měi yīgè zhízǐ dōu zhànyòng bùtóng de néng jí, zhōng zǐ de qíngkuàng yě yǔ cǐ xiāngtóng. Bùguò pào lì bù xiāng róng yuánlǐ bìng méiyǒu jìnzhǐ yīgè zhízǐ hé yīgè zhōng zǐ yǒngyǒu xiāngtóng de liàngzǐ tài. Rúguǒ yīgè yuánzǐhé de zhízǐ shù hé zhōng zǐ shǔ bù xiāngtóng, nàme gāi yuánzǐhé hěn róngyì fāshēng fàngshèxìng shuāibiàn dào yīgè gèng dī de néng jí, bìngqiě shǐdé zhízǐ shù hé zhōng zǐ shù gèngjiā xiāngjìn. Yīncǐ, zhízǐ shù hé zhōng zǐ shù xiāngtóng huò hěn xiāngjìn de yuánzǐ gèngjiā bù róngyì shuāibiàn. Rán'ér, dāng yuánzǐ xùshù zhújiàn zēngjiā shí, yīnwèi zhízǐ zhī jiān de páichì lì zēngqiáng, xūyào gèng duō de zhōng zǐ lái shǐ zhěnggè yuánzǐhé biàn de wěndìng, suǒyǐ duì shàngshù qūshì yǒu suǒ yǐngxiǎng. Yīncǐ, dāng yuánzǐ xùshù dà yú 20 shí, jiù bùnéng zhǎodào yīgè zhízǐ shù yǔ zhōng zǐ shù xiāngděng ér yòu wěndìng de yuánzǐhéle. Suízhe Z de zēngjiā, zhōng zǐ hé zhízǐ de bǐlì zhújiàn qū yú 1.5. Hé jùbiàn shìyìtú, tú zhōng liǎng gè zhízǐ jùbiàn shēngchéng yīgè bāohán yǒu yīgè zhízǐ hé yīgè zhōng zǐ de dāo yuánzǐhé, bìng shìfàng chū yīgè zhèng diànzǐ (diànzǐ de fǎnwùzhí) yǐjí yīgè diànzǐ zhōng wēi zi. Yǔ cǐ xiāngfǎn de guòchéng shì hé lièbiàn. Rúguǒ hé jùbiàn hòu chǎnshēng de yuánzǐhé zhí liàng xiǎoyú jùbiàn qián yuánzǐ zhìliàng de zǒnghé, nàme gēnjù ài yīn sītǎn de zhí néng fāngchéng, zhè yīxiē zhìliàng de chà jiù zuòwéi néngliàng bèi shìfàngle. Zhège chābié shíjì shì yuánzǐhé zhī jiān de jiéhé néng, duìyú liǎng gè yuánzǐ xùshù zài tiě huò niè zhīqián de yuánzǐhé lái shuō. Zài a lìzǐ sǎnshè shíyàn zhōng, rénmen fāxiàn, yuánzǐ de zhìliàng jízhōng yú yīgè hěn xiǎo qiě dài zhèng diàn de wùzhí zhōng, zhè jiùshì yuánzǐhé. Yuánzǐhé yě chēng zuò hézǐ, yóu yuánzǐ zhōng suǒyǒu de zhízǐ hé zhōng zǐ zǔchéng, yuánzǐhé de bànjìng yuē děngyú 1.07×A^1/3 fm, qízhōng A shì hézǐ de zǒngshù. Yuánzǐ bànjìng de shùliàngjí dàyuē shì 105fm, yīncǐ yuánzǐhé de bànjìng yuǎn yuǎn xiǎoyú yuánzǐ de bànjìng.展开949/5000All the protons and neutrons in an atom combine to form a very small nucleus, and together they can also be called nucleons. The radius of the nucleus is approximately equal to 1.07×A^1/3 fm, where A is the total number of nuclei. The order of the atomic radius is about 105 fm, so the radius of the nucleus is much smaller than the radius of the atom. The nuclei are bound together by residual strong forces that can work at short distances. When the distance is less than 2.5fm, the strength is far greater than the electrostatic force, so it can overcome the mutual repulsion between positively charged protons.
Atoms of the same element have the same number of protons, and this number is also called the atomic number. For a particular element, the number of neutrons can vary, which determines which isotope of the element the atom is. The number of protons and neutrons determines which type of element the atom is. The number of neutrons determines the stability of the atom, and some isotopes can spontaneously undergo radioactive decay. Neutrons and protons are both types of fermions. According to the Pauli exclusion principle in quantum mechanics, it is impossible for two identical fermions to have the same quantum physical state at the same time. Therefore, each proton in the nucleus occupies a different energy level, and the same is true for neutrons. But Pauli’s exclusion principle does not prohibit a proton and a neutron from having the same quantum state.
If the number of protons and neutrons of an atomic nucleus are not the same, then the nucleus is prone to radioactive decay to a lower energy level and makes the number of protons and neutrons more similar. Therefore, atoms with the same or very similar number of protons and neutrons are less prone to decay. However, when the atomic number gradually increases, because the repulsive force between protons increases, more neutrons are needed to stabilize the entire nucleus, which affects the above trend. Therefore, when the atomic number is greater than 20, a stable nucleus with the same number of protons and neutrons cannot be found. As Z increases, the ratio of neutrons to protons gradually tends to 1.5.
A schematic diagram of nuclear fusion. In the picture, two protons fused to form a deuterium nucleus containing a proton and a neutron, and released a positron (the antimatter of an electron) and an electron neutrino. The opposite process is nuclear fission.
If the mass of the atomic nucleus produced after nuclear fusion is less than the sum of the atomic masses before the fusion, then according to Einstein's mass-energy equation, these mass differences are released as energy. This difference is actually the binding energy between nuclei, for two nuclei with atomic numbers before iron or nickel.
In the alpha particle scattering experiment, people found that the mass of the atom is concentrated in a small and positively charged substance, which is the nucleus.
The nucleus is also called a nucleus and consists of all the protons and neutrons in the atom. The radius of the nucleus is approximately equal to 1.07×A^1/3 fm, where A is the total number of nucleons. The order of the atomic radius is about 105 fm, so the radius of the nucleus is much smaller than the radius of the atom.