Why do all the Isotopes of an Element have similar Chemical Properties?

The fundamental building units of matter are atoms and molecules. The existence of many types of matter is due to the various atoms that contain them. The atom was no longer seen as a simple, indivisible unit by 1900. It did, however, contain at least one subatomic particle, the electron. J.J. Thomson was the one who discovered it. E Goldstein discovered the presence of electrons in 1886. An electron is usually denoted by the letter e^–, while a proton is denoted by the letter p⁺.

The number of protons that a chemical element has in its nucleus is called its atomic number. For example- The atomic number of Hydrogen is 1. The total number of protons and neutrons in an atom is called its mass number. For example- the mass number of Carbon is 12 (6 protons and 6 neutrons.)

What are Isotopes?

Isotope is a variant of an element where it has an equal number of protons but a different number of neutrons of the atom due to which, the isotopes have different masses. Elements with an odd atomic numbers like Hydrogen, Lithium, Sodium or Nitrogen have one or two stable isotopes. Elements with even atomic number like Sulphur or Oxygen is more likely to have at least 3 stable isotopes. The exceptions here are carbon, helium, and beryllium.

Properties of isotopes:

1. Chemical Properties: The chemical properties are almost identical as different isotopes show almost identical chemical behaviours.
2. Physical Properties: Physical properties like mass, melting or boiling point, density, and freezing point are different and depends on the mass of each isotope.
3. Isotopes are either stable or radioactive.
4. Radioactive isotopes are called radioisotopes or radionuclides.
5. Isotopes that do not decay radioactively are called stable isotopes or stable nuclides.

Isotopes of Hydrogen and Carbon

Hydrogen has three stable isotopes called protium, deuterium, and tritium. All three of them have a same number of protons but a different number of neutrons. Deuterium has one neutron and tritium has two. Protium has zero neutrons while deuterium has one and tritium has two.

Carbon has three isotopes namely Carbon-12 (stable isotope), Carbon-13, and Carbon-14 (radioactive isotope) where 12, 13, and 14 are the isotopes’ atomic masses.

Isotopes and Nuclides

A nuclide is a species of an atom with a specific number of protons and neutrons in the nucleus. E.g. carbon-13 with 6 protons and 7 neutrons. Nuclear qualities are prioritized over chemical properties in the nuclide idea. Chemical isotopes are prioritized over nuclear isotopes in the isotope idea. Even for the lightest elements, it usually has only a minor impact, though it can be significant in some cases.

All the Isotopes of an Element Have Identical Chemical Properties

All the Isotopes of an element have identical chemical properties because they have the same number of electrons as an atom of that element but they have different numbers of neutrons. The different number of neutrons affects the mass number. The mass number determines the physical properties while the atomic number determines the chemical properties. Therefore, isotopes have similar chemical properties but different physical properties.

Radioisotopes, radionuclides, and radioactive nuclides are all terms used to describe radioactive isotopes. At least one radioactive isotope exists for each chemical element. Hydrogen, for example, has three isotopes with mass numbers 1, 2, and 3, with tritium being radioactive and the other two being stable. There are about 1,000 radioactive isotopes of the elements known, with 50 of them occurring naturally and the rest being created artificially as direct products of nuclear processes or as radioactive descendants of these products. The half-life of a substance is the time it takes for its radioactivity to decline to half of its original value.

Applications of Isotopes

1. Medical Field: Cobalt-60 is a radiation source used in medicine to slow the progression of cancer. Other radioactive isotopes are employed as tracers in metabolic research and for diagnostic purposes. In a breath test, carbon-14 is utilised to detect the ulcer-causing bacteria Helicobacter pylori.
2. Industry: Radioactive isotopes are employed in industry to measure the thickness of metal or plastic sheets, with the strength of the radiations that penetrate the substance being investigated indicating the precise thickness. They can also be utilised as small electrical power sources. Plutonium-238 in spacecraft is an example.

Sample Questions

Question 1: Define mass number and atomic number.

Answer:

The number of protons that a chemical element has in its nucleus is called its atomic number. For example- The atomic number of Hydrogen is 1. The total number of protons and neutrons in an atom is called its mass number. For example- the mass number of Carbon is 12 (6 protons and 6 neutrons.)

Question 2: What are isotopes and isobars?

Answer:

Isotope is a variant of an element where the variant will have equal number of protons but would differ in the number of neutrons of the atom. Isobars are atoms that have same number of nucleons. Isobars of different chemical elements have different atomic number but have the same mass number.

Question 3: What are the isotopes of Hydrogen and Carbon? 

Answer:

Hydrogen has three stable isotopes called protium, deuterium, and tritium. All three of them have same number of protons but a different number of neutrons. Deuterium has one neutron and tritium has two. Protium has zero neutrons while deuterium has one and tritium has two.

Carbon has three isotopes namely Carbon-12 (stable isotope), Carbon-13, and Carbon-14 (radioactive isotope) where 12, 13, and 14 are the isotopes’ atomic masses.

Question 4: What are the chemical and physical properties of isotopes? 

Answer:

The chemical properties of isotopes of a given element are almost identical as different isotopes show almost identical chemical behaviors. Physical properties of an isotopes like mass, melting or boiling point, density, and freezing point are different and depends on the mass of each isotope.

Question 5: Why do all the Isotopes of an Element Have Identical Chemical Properties?

Answer:

All the Isotopes of an element have identical chemical properties. The reason for this is because isotopes of an element have the same number of electrons as an atom of that element but they have different number of neutrons which affects the mass number. Mass number determines the physical properties while atomic number determines the chemical properties. Therefore, isotopes have similar chemical properties but different physical properties.