什么是同位素？

在《原子结构》中，我们看到了不同类型的原子模型，如汤姆森模型、卢瑟福模型等，从那里我们了解了原子质量和数量等术语。在自然界中，科学家们发现了几种具有相同原子质量或相同原子序数的元素，为了对这些元素有一个清晰的认识，将它们分为几类，分别命名为同位素、等压线、同位素， 等等

同位素

考虑两个具有相同颜色和相同物理外观的对象，您无法将它们区分开来。但是，当比较这两个项目的权重时，会发现它们是不同的。这个例子可以帮助你理解同位素的概念。

众所周知，原子由电子、质子和中子组成。原子核由质子和中子组成，而电子围绕它运行。原子质量是质子数和中子数之和，而原子序数等于质子数。元素中的质子数是恒定的，而中子数是变化的。

Isotopes are atoms in which the number of neutrons varies but the number of protons remains constant. Based on the definitions of atomic mass and atomic number provided above, we may deduce that isotopes are elements that have the same atomic number but a different mass number. 

或者换句话说，质子数相同但中子数不同的元素称为同位素。例如¹ H ₁ (氕)、 ² H ₁ (氘) _、 ³ H ₁ (氚)是氢的同位素。

放射性同位素的应用

放射性同位素有多种应用。然而，一般来说，它们是有用的，因为我们可以检测它们的放射性，或者我们可以使用它们释放的能量。它们经常用于医药、工业和农业，用于各种有用的目的。放射性同位素的主要作用是用作示踪剂。

示踪剂是一种化合物，其中一个或多个原子已被放射性核素取代，因此由于其放射性衰变，它们用于追踪放射性同位素的路径，因此具有多种用途。

以下是放射性同位素的应用：

1. 放射性测年：确定含碳物体年龄的放射性碳测年使用放射性同位素碳 14。因为放射性同位素的半衰期不受外部变量的影响，所以同位素起到了内部时钟的作用。
2. 食品辐照：一些放射性化合物产生的辐射可用于破坏一系列商品上的细菌，从而延长其保质期。西红柿、蘑菇、豆芽和浆果都用钴 60 或铯 137 排放物进行辐照。
3. 医疗应用：放射性同位素提供广泛的医疗用途，包括疾病的诊断和治疗。例如， ³² P 用于癌症的识别和治疗，特别是在眼睛和皮肤中， ⁵⁹ Fe 用于贫血诊断， ⁶⁰ Co 用于肿瘤伽马射线照射， ¹³¹ I 用于甲状腺函数诊断和治疗等等。
4. 其他用途：放射性同位素可用于农业、食品工业、害虫防治、考古学和医学。

等压线

等压线是具有不同化学性质但物理性质相同的元素。因此，等压线是具有不同原子序数但质量数相同的元素。它们的化学性质因电子数量的变化而不同。它具有与另一个相同的原子质量，但原子序数不同。因为中子数量的增加弥补了核子数量的差异。

Elements that have the same mass number or one can say same atomic mass are known as Isobars. e.g. ⁴⁰Ar₁₈ (Argon) and ⁴⁰Ca₂₀ (Calcium) are examples of Isobars as they have same mass number (i.e. 40).

等压线示例

放射性等压线的应用

1. 等压钴用于治疗癌症
2. 磷等压线用于治疗血癌
3. 碘用于治疗甲状腺疾病
4. 等压线用于治疗肿瘤、血栓等。
5. 此外，它们还可用于气象和天气图。

基于同位素和等压线的问题

问题 1：区分同位素和等压线？

解决方案：

Following are the differences between Isotopes and Isobars-

	Isotopes	Isobars
1.	Isotopes are atoms with the same number of protons but differ in numbers of neutrons.	Isobars are atoms of different chemical elements having equal values for atomic mass
2.	Isotopes of an element have the same chemical properties	Isobars differ in their chemical properties
3.	Isotopes occur in the same place in the periodic table.	Isobars occur at a different place in the periodic table.
4.	Isotopes have different physical properties from each other	Isobars mostly have similar physical properties.
5.	Similar arrangement and number of electrons	Arrangement of electrons are different.
6.	They are atoms of the same element.	They are atoms of different elements.

问题 2：同位素具有相同的化学性质，而等压线不具有相同的化学性质。为什么？

解决方案：

Isotopes of an element have the same number of electrons and protons but have the different numbers of neutrons. Since the chemical properties of elements depend upon the atomic number, isotopes of an element have simile chemical properties.

On the other hand, isobars have the different numbers of electrons, protons as well as neutrons.

Thus, isobars have different chemical properties.

问题3：原子中的质子数和电子数相同，为什么说原子的原子序数等于它的电子数是错误的？

解决方案：

It is right to say that the atomic number of an atom is equal to no. of electrons in that atom, but it is correct only for the neutral atom which means the atom having neither positive nor negative charge. If there is an ion in which either no of electrons are less or more than electron then we cannot say that atomic number is equal to the number of electrons.

问题 4：放射性同位素和简单的同位素术语之间的主要区别是什么？

解决方案：

An Isotope is an atom of an element with a different number of neutrons than the original element. e.g. Carbon usually has 6 neutrons. An Isotope of carbon would be carbon 13. This atom is an isotope because it has 7 neutrons instead of 6.

However, Radioisotope is also an isotope by nature. The difference is that radioisotopes are very unstable and contain high levels of nuclear energy and emit this energy in the form of nuclear radiation. The main difference: Isotopes can be stable or unstable, but Radioisotopes are always unstable.

问题5：放射性同位素是如何产生的？

解决方案：

There are several sources of radioactive isotopes. Some radioactive isotopes are present as terrestrial radiation. Radioactive isotopes of radium, thorium, and uranium, for example, are found naturally in rocks and soil. Uranium and thorium also occur in trace amounts in water. Radon, generated by the radioactive decay of radium, is present in the air. 

Organic materials typically contain small amounts of radioactive carbon and potassium. Cosmic radiation from the Sun and other stars is a source of background radiation on Earth. Other radioactive isotopes are produced by humans via nuclear reactions, which result in unstable combinations of neutrons and protons. One way of artificially inducing nuclear transmutation is by bombarding stable isotopes with alpha particles.

问题 6：癌症治疗中使用了哪些同位素，为什么？

解决方案：

Yttrium-90 is used for the treatment of cancer, particularly non-Hodgkin’s lymphoma and liver cancer, and it is being used more widely, including for arthritis treatment. Lu-177 and Y-90 are becoming the main RNT agents.

A large dose of radiation caused reddening of the skin, damage to tissues, radiation necrosis, sterility. Small animals could be killed. Such damage to growing matter suggested that cancer might be treated by the new radiation. Little was known about the cause or mechanism of cancer, but its manifestation as an uncontrollable “growth” was easy to see, and surgeons treated cancer by cutting away the diseased part. Could radiation replace surgery? The experiment showed that apparently, it could. Not only did radiation inhibit the growth of these malignant cells, but it seemed to be more effective against them than against normal body tissues. On this last fortunate fact depends on the successful treatment of cancer by radiation. It is the basis for radiotherapy, the new medical discipline that grew out of Roentgen’s discovery.