Process of ionization
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The document discusses ionization, the process of atoms or molecules gaining or losing electrons to form ions, including methods of production, energy trends, and applications. It covers classical and quantum mechanical descriptions of ionization, highlighting differences in phenomena like tunnel ionization and photoionization. Additionally, it distinguishes between dissociation and ionization, using examples like sugar and salt to illustrate the concepts.
Process of ionization
- 1. Process of Ionization Presenting By :- 1. Ankkit Ghag 2. Hritika Ghosalkar 3. Aakanksha Ghadi 4. Vidhit Chotaliya 5. Sanket Muchhala Polytechnic 1St Year EJ
- 2. Table Of Content 1) Introduction 2) Uses 3) Production of ions 4) Ionization energy of atoms 5) Semi-classical description of ionization 6) Quantum mechanical description of ionization 7) Dissociation – distinction
- 3. Introduction Ionization is the process by which an atom or a molecule acquires a negative or positive charge by gaining or losing electrons to form ions, often in conjunction with other chemical changes. Ionization can result from the loss of an electron after collisions with subatomic particles, collisions with other atoms, molecules and ions, or through the interaction with light. Heterolytic bond cleavage and heterolytic substitution reactions can result in the formation of ion pairs. Ionization can occur through radioactive decay by the internal conversion process, in which an excited nucleus transfers its energy to one of the inner-shell electrons causing it to be ejected.
- 4. Uses Uses :- Everyday examples of gas ionization are such as within a fluorescent lamp or other electrical discharge lamps. It is also used in radiation detectors such as the Geiger-Müller counter or the ionization chamber. The ionization process is widely used in a variety of equipment in fundamental science (e.g., mass spectrometry) and in industry (e.g., radiation therapy).
- 5. Production of ions Negatively charged ions are produced when a free electron collides with an atom and is subsequently trapped inside the electric potential barrier, releasing any excess energy. The process is known as electron capture ionization. Positively charged ions are produced by transferring a sufficient amount of energy to a bound electron in a collision with charged particles (e.g. ions, electrons or positrons) or with photons. The threshold amount of the required energy is known as ionization potential. The study of such collisions is of fundamental importance with regard to the few-body problem (see article on few-body systems), which is one of the major unsolved problems in physics.
- 6. Ionization energy of atoms The trend in the ionization energy of atoms is often used to demonstrate the periodic behavior of atoms with respect to the atomic number, as summarized by ordering atoms in Mendeleev's table. This is a valuable tool for establishing and understanding the ordering of electrons in atomic orbitals without going into the details of wave functions or the ionization process.
- 7. Semi-classical description of ionization Classical physics and the Bohr model of the atom can qualitatively explain photoionization and collision-mediated ionization. In these cases, during the ionization process, the energy of the electron exceeds the energy difference of the potential barrier it is trying to pass. The semi-classical description, however, cannot describe tunnel ionization since the process involves the passage of electron through a classically forbidden potential barrier.
- 8. Quantum mechanical description of ionization The interaction of atoms and molecules with sufficiently strong laser pulses leads to the ionization to singly or multiply charged ions. The ionization rate, i.e. the ionization probability in unit time, can only be calculated using quantum mechanics. In general, the analytic solutions are not available, and the approximations required for manageable numerical calculations do not provide accurate enough results. However, when the laser intensity is sufficiently high, the detailed structure of the atom or molecule can be ignored and analytic solution for the ionization rate is possible.
- 9. Dissociation – distinction A substance may dissociate without necessarily producing ions. As an example, the molecules of table sugar dissociate in water (sugar is dissolved) but exist as intact neutral entities. Another subtle event is the dissociation of sodium chloride (table salt) into sodium and chlorine ions. Although it may seem as a case of ionization, in reality the ions already exist within the crystal lattice. When salt is dissociated, its constituent ions are simply surrounded by water molecules and their effects are visible (e.g. the solution becomes electrolytic). However, no transfer or displacement of electrons occurs. Actually, the chemical synthesis of salt involves ionization. This is a chemical reaction.
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