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The same atomic number but the different mass number is a characteristic of isotopes. The structure of an atom is known as atomic structure. The atomic structures of isotopes are the arrangement of the sub-atomic particles of the isotopes of an element. Three subatomic particles of atoms are protons (positively charged), neutrons (no charge), and electrons (negatively charged). The atom’s nucleus is made up of positively charged protons and neutrons, while the negatively charged electrons move around it in circular orbits. The total number of protons in the nucleus is the Atomic number of that element. The mass number is the sum of the total number of protons and neutrons in an atom.
History
- In the 1800s Scientist John Dalton proposed Dalton’s Atomic theory where he stated that different properties of atoms like every matter are made up of atoms. Atoms are indivisible units, a particular element has a similar type of atoms. Atoms can neither be created nor be destroyed; they can just undergo rearrangements.
- In the 1900s J.J. Thomson discovered the electrons and gave us the famous Plum-Pudding model.
- Then Rutherford discovered that the central part of an atom is positively charged and named it the nucleus. He also put forward theories like electrons which are negatively charged particles that move around the nucleus in orbits.
- Then came Bohr’s model of an atom
Subatomic Particles of an atom
Particle | Proton | Neutron | Electron |
Mass | 1.6726 × 10-27 Kg | 1.6750 × 10-27 Kg | 9.1095 × 10-31 Kg |
Charge | + 1.6022 × 10-19 | 0 | −1.6022 × 10-19 |
Basics
Total no. of protons = Atomic Number (Z)
Isotopes of an element have the same no. of protons but different neutrons.
Mass number (A) = No. of protons + No. of neutrons.
No. of protons = No. of electrons
Atomic Structures of Isotopes Notes
Structure of an atom is called Atomic structure.
Isotopes are types of an atom that have the same number of protons and the different number of neutrons.
The difference in the number of neutrons changes the atomic mass of the isotopes of the element.
In other words, isotopes of an element have the same Atomic number (Z) but different Mass Numbers (A).
Hence the isotopes of an element are placed in the same respective position as that of the original element in the periodic table.
The isotopes of an element have the same electronic configuration as the atomic number is the same.
The isotopes of an element show similar chemical properties because the electron determines the chemical behaviour of an element. In isotopes, the no. of electrons remains the same hence they show similar chemical properties.
Examples of different isotopes and their atomic structures
Isotopes of hydrogen
Protium, Deuterium and Tritium
Protium – it contains 1 proton + 1 electron. The atomic no. is 1 and the mass no. is also 1
Deuterium- It contains 1 proton + 1 neutron. The atomic no. is 1 but the mass no. is 2 in this case.
Tritium- contains a proton + 2 neutrons. The atomic no. is 1 but the mass no. is 3.
Carbon isotopes
12C, 13C, and 14C.
12C- it contains 6 neutrons + 6 protons. It has an atomic no. 6 whereas the mass no. is 12
13C- it contains 7 neutrons + 6 protons. The atomic no. is 6 whereas the mass no. is 13
14C- it has 8 neutrons + 6 protons. The atomic no. is 6 and the mass no. is 14.
Isotopes of oxygen
16O, 17O, and 18O.
16O- 8 protons + 8 neutrons. The atomic no. is 8 but the mass no. is 16
17O- 8 protons + 9 neutrons. The atomic no. here is 8 but the mass no. is 17
18O- contains 8 protons + 10 neutrons. The atomic no. is 8 while the mass no. is 18.
Isotopes of Chlorine
37Cl and 35Cl.
35Cl contains 17 protons + 18 electrons.
37Cl has 17 protons + 20 neutrons.
Uses of Isotopes:
Isotopes of carbon are used in carbon dating and the study of fossils.
Few isotopes also have great importance in determining the biological processes happening in the human body.
It can also be used to diagnose different diseases.
Conclusion
: The atom consists of Three subatomic particles being protons (positively charged), neutrons (no charge), and electrons (negatively charged). The atomic structures of isotopes are different as the mass number of Isotopes is different. While the electronic configuration of isotopes is the same, the atomic number of isotopes is the same. Hence mass number and atomic number play a very important role in determining the position and behaviour of an atom. The isotopes of an element are also known for various uses in different industries.
