Section outline

  • General

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  • 放射性

    Pressurized Water Reactors (PWRs) used in military vessels for nuclear power generation.

    The machines in the image are Pressurized Water Reactors (PWRs). These are small used for the generation of power. Primarily the nuclear is used to change water into steam and the steam then runs the machinery. Several hundred PWRs are used for propulsion in military vessels such as aircraft carriers, submarines, and ice breakers. These nuclear reactors were originally designed at the Oak Ridge National Laboratory for use as nuclear submarine power plants.
    ::图像中的机器是加压水反应堆(PWRs),用于发电的机体很小,主要是核能用于将水转化为蒸汽,然后蒸汽操作机器,几百个PWRs用于推进军用船只,如航空母舰、潜艇和破冰器,这些核反应堆最初设计在橡树脊国家实验室,用作核潜艇发电厂。

    Radioactivity

    ::放射性

    The total mass of a stable nucleus is always less than the sum of the masses of its constituent protons and neutrons . This is known as mass defect . As an example of this, consider the mass of a @$\begin{align*}^4_2 He\end{align*}@$  nucleus compared to the sum of the masses of its constituent nucleons.
    ::稳定核的总质量总是小于其质子和中子质量的总和。 这被称为质量缺陷。 例如, 考虑一个@$\ begin{ align}4_ 2 He\end{ align}$核心的质量, 与其组成核质量的总和相比较 。

    The mass of a @$\begin{align*}^4_2 He\end{align*}@$  nucleus is 4.002603 amu. The mass of two neutrons and two protons is @$\begin{align*}(2)(1.008665 \ \text{amu}) + (2)(1.007825 \ \text{amu}) = 4.032980 \ \text{amu}\end{align*}@$ . Thus, the mass of the helium-4 nucleus is 0.030377 amu less than the masses of its constituents. The lost mass has gone into energy that is called binding energy . The binding energy is equal to the amount of energy that would have to be put into the helium-4 nucleus in order to break it into its constituent protons and neutrons. Without the binding energy, the repulsion between the protons would blow this nucleus apart. We often refer to the average binding energy per nucleon which is defined as the total binding energy of a nucleus divided by the number of nucleons in the nucleus.
    ::$@ begin{ align} 4_ 2 Heend{ align} $核心的质量为 4. 002603 amu。 两个中子和两个质子的质量为 @ $\ begin{ align} (2)1. 008665\\\ text{ amu}) + (2)1. 007825\\\\ text{ amu} = 4. 032980\\\ text{ amu} {end{ align} $。 因此, -4 核的重量比其成分质量小0. 030377 amu amu。 损失的质数已进入能量中, 被称为约束能量。 约束能量等于需要投入到-4 核核心中的能量数量, 才能打破其组成质子和中子 。 没有约束能量, 质子之间的反作用会吹散这个核。 我们经常提到每个核的均装能量, 被定义为核心中核中核中核的完全约束能量。

    Each nucleus, therefore, has competing forces. The repulsive force between the protons tends to blow the nucleus apart and the binding energy tends to hold the nucleus together. If the average binding energy per nucleon overcomes the repulsion, the nucleus stays together and it referred to as stable. If the repulsion overcomes the average binding energy per nucleon, the nucleus may blow apart or undergo nuclear disintegration . When a nucleus disintegrates, it throws off pieces of itself and energy in the form of . This disintegration process came to be called radioactivity .
    ::因此,每个核都有相互竞争的力量。质子之间的可憎力量往往把核分开,而紧凑的能量往往将核凝聚在一起。如果每个核平均装订的能量克服了反射,核就保持在一起,它被称为稳定。如果反作用克服了每个核平均装订的能量,核就可能会破裂或发生核解体。当核分解时,核会以辐射的形式抛出自己的碎片和能量。这种分解过程被称为放射性过程。

    Early researchers in radioactivity found that the emissions from radioactivity could be classified into three distinct types according to their penetrating power. One type of radiation could barely penetrate a sheet of paper. The second type could pass through as much as 3 mm of aluminum. The third type was extremely penetrating and could pass through several centimeters of lead. They named these three types of radiation alpha @$\begin{align*}(\alpha)\end{align*}@$ , beta @$\begin{align*}(\beta)\end{align*}@$ , and gamma @$\begin{align*}(\gamma)\end{align*}@$  respectively. Eventually, each type of radiation was further identified. Alpha particles are the nuclei of helium atoms, @$\begin{align*}^4_2 He\end{align*}@$ . Beta particles are electrons, and gamma rays are very high energy photons (even higher energy than x-rays).
    ::早期放射性研究者发现,放射性排放根据其穿透力可分为三种不同类型。 一种辐射几乎无法穿透纸张。 第二种辐射可以穿透多达3毫米的铝。 第三种辐射非常透透, 可以穿透几厘米的铅。 他们列出了这三种类型的辐射α@ $\ begin{ align}( ALpha)\end{ align}$、 bita@ begin{ align}( \ beta)\ end{ aliign}\ end{ leign} $, 和 gama@\ begin{ allign}( \ gamma)\ end{ leign} $。 最终, 每一种辐射都得到了进一步确认。 阿尔法粒子是原子的核核, @\ begin { { 4_ 2 Heend{ { leign $. Beta 粒子是电子, 伽玛射线是非常高的能量光( 甚至高于X射线)。 </span> </p> <button class="play-button btn btn-success" style="float: right;" value="@s"> 播放段落 </button> <p id="x-ck12-ZTMwMjVkNDU5NmFkZmVhMWYzZGYzNjMxZTAzMTZjMDI.-jvu"> When a nucleus emits an  <span class="x-ck12-mathEditor" data-contenteditable="false" data-edithtml="" data-math-class="x-ck12-math" data-mathmethod="inline" data-tex="%5Calpha"> @$\begin{align*}\alpha\end{align*}@$ particle, the remaining particle will contain two less protons and two less neutrons.  The new particle will have an atomic number two less and a mass number four less than the original nuclide .
    ::当核发出一个@$\ begin{ align} alpha\ end{ align} $ 粒子时, 剩下的粒子将包含两个小质子和两个小中子。 新的粒子将拥有一个原子号二比原核素少, 质量号四比原核素少。

    @$$\begin{align*}^{226}_{88} Ra \longrightarrow {^{222}_{86}Rn}+ {^4_2 He}\end{align*}@$$
    ::@ $\ begin{ align} @ 226 @ 88} Ra\ longrightrow { 2222_ 86} Rn} @ @ 4_ 2_ Heend{ align} $

    The daughter product, @$\begin{align*}^{222}_{86} Rn\end{align*}@$ , is different from the parent nucleus, @$\begin{align*}^{226}_{88} Ra\end{align*}@$ , by two protons and two neutrons. This changing of one element into another is called transmutation .
    ::女儿的产物, @$\ begin{ align22286} Rn\ end{ align$, 与父核不同, @ $\ begin{ align} @ 22688} Ra\ end{ align$, 由两个质子和两个中子组成。 将一个元素转换成另一个元素, 叫做“ 变换 ” 。 </span> </p> <button class="play-button btn btn-success" style="float: right;" value="@s"> 播放段落 </button> <p id="x-ck12-ZDY3M2Q3NzUwZmMwMjZkMDVmOWVlMDI0OGFkOTcwZGY.-4do"> Transmutation also occurs when a nucleus undergoes  <span class="x-ck12-mathEditor" data-contenteditable="false" data-edithtml="" data-math-class="x-ck12-math" data-mathmethod="inline" data-tex="%5Cbeta"> @$\begin{align*}\beta\end{align*}@$ decay. An example of beta decay is the emission of an electron by a carbon-14 nucleus.
    ::当核发生@$\ begin{ align\ beta\ end{ aliign} $ 衰变时, 也会出现变性。 乙型衰变的例子之一是碳-14核释放电子。

    @$$\begin{align*}^{14}_6 C \longrightarrow {^{14}_7 N}+{^0_{-1} e}\end{align*}@$$
    ::@ $\ begin{ ALIGN} $14\ 14\ 6 C\ longrightrow @ 14\ 7 N @ 0\ -1} e{ end{ ALIGN} $

    The symbol @$\begin{align*}{^0_{-1}e}\end{align*}@$  represents an electron whose charge corresponds to  @$\begin{align*}Z=-1\end{align*}@$ and since it has no nucleons, @$\begin{align*}A=0\end{align*}@$ . It must be carefully noted that the electron released during beta decay is NOT an orbital electron but an electron whose origin was in the nucleus. The process has one neutron becoming one proton and one electron and the electron being emitted as a beta particle. Since a neutron has been lost AND a proton has been gained, the mass number does not change. The atomic number, however, has increased one due to the gain of a proton.  Therefore, as a result of beta decay, the daughter product will have the same mass number as the parent and an atomic number one greater than the parent.
    ::符号@ $\ begin{ align@ 0_ 1} e{ end{ align} $ 代表一种电子, 其电量相当于 @ $\ begin{ align}-1\ end{ align} $, 并且由于它没有核子, @ $\ begin{ align}}A=0\ end{ align} $。 必须指出, 乙型衰变过程中释放的电子不是轨道电子, 而是原产于核的电子。 这一过程有一个中子变成一个质子和一个电子, 电子作为乙型粒子被排放。 由于中子已经丢失, 质子已经获得, 质量没有变化。 但是原子数由于质子的增益, 原子数增加了一个。 因此, 由于乙型衰减, 女儿产物的质数将和母体相同, 原子数比母体更大。

    Launch the simulation below to become a student in Marie Curie’s classroom and  study the radioactive decay of heavy nuclei :
    ::并研究重核的放射性衰减:

    Further Reading
    ::继续阅读

    Summary
    ::摘要

    • The total mass of a stable nucleus is always less than the sum of the masses of its constituent protons and neutrons. This is known as mass defect.
      ::稳定核的总质量总是低于其组成质子和中子质量的总和,这被称为质量缺陷。
    • The mass lost in mass defect has gone into energy that is called binding energy.
      ::在质量缺陷中损失的重量 已经进入了能源, 即所谓的连锁能源。
    • Each nucleus has competing forces. The repulsive force between the protons tends to blow the nucleus apart and the binding energy tends to hold the nucleus together.
      ::每个核都有相互竞争的力量。质子之间的可憎力量往往会把核分开,而紧凑的能量往往会把核放在一起。
    • If the repulsion overcomes the average binding energy per nucleon, the nucleus may blow apart or undergo nuclear disintegration.
      ::如果反弹克服了每个核的平均装配能量,核核可能会破裂或核解体。
    • Early researchers in radioactivity found that the emissions from radioactivity could be classified into three distinct types according to their penetrating power. They named these three types of radiation alpha @$\begin{align*}(\alpha)\end{align*}@$ , beta @$\begin{align*}(\beta)\end{align*}@$ , and gamma  @$\begin{align*}(\gamma)\end{align*}@$ respectively.
      ::早期放射性研究人员发现,放射性排放根据其穿透能力可分为三种不同类型。 他们分别命名这三种辐射类型为: Alpha@$\ begin{align}(\ alpha)\end{align}$, beta@\ begin{align}}(\beta)\end{align}$, 和伽马@$\ begin{align}(\ gamma)\end{align}$。
    • When a nucleus emits an  @$\begin{align*}\alpha\end{align*}@$ particle, the remaining particle will contain two less protons and two less neutrons.
      ::当核发出@$\ begin{ align} alpha\ end{ align} $ 粒子时, 剩下的粒子将包含两个小质子和两个小中子。
    • As a result of beta decay, the daughter product will have the same mass number as the parent and an atomic number one greater than the parent.
      ::由于乙型腺衰变,女儿产物的质数将与母体相同,原子数比母体大。

    Review
    ::回顾

    1. Write the nuclear equation showing beta decay of a copper-64 nucleus.
      ::写核方程式 显示铜-64核的贝塔衰减
    2. Write the nuclear equation showing the alpha decay of a uranium-238 nucleus.
      ::写核方程式 显示铀238核的阿尔法衰减
    3. What element is formed by the beta decay of sodium-24?
      ::24钠的乙型衰减构成什么元素?
    4. What element is formed by the alpha decay of bismuth-211?
      ::丁基-211的α衰变构成什么元素?

    Explore More
    ::探索更多

    Use this resource to answer the questions that follow.
    ::使用此资源回答下面的问题 。

     

    1. What is radiation? How can we measure it?
      ::什么是辐射?我们如何测量它?
    2. How does a Geiger counter work?
      ::盖革计数器怎么用?
    3. What is responsible for the static coming from a Geiger counter?
      ::从盖革柜台传来的静电是什么呢?
    4. What prevents protons from repulsing each other?
      ::是什么阻止质子互相击退呢?