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Physical chemistry is the branch of chemistry dealing at atomic, subatomic or molecular level. It studies the behavior of matter of atoms or molecules at different scales from macroscopic to subatomic scale. Physical chemistry is different from other branches of chemistry. It uses the concepts of physics and its principles to understand chemical systems and reactions.
Read also: Properties of Matter
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Key Terms: Physical Chemistry, chemistry, theories, atomic and subatomic scales, atoms and molecules
What is Physical Chemistry?
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Physical chemistry deals with material interactions and changes. Unlike other chemical branches it is based on principles of physics in chemical interaction and reactions. The aim to focus on physical principles in chemistry is correlating, measuring and quantitative response features. By using smaller particles, atoms and molecules, quantum mechanism clarifies physical chemistry to use computers and advanced mathematical techniques to understand how the chemical reactions work or what's happening in the chemical reactions.
Read More: Energy Level Diagram
Different Scales of Physical Chemistry
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The branches of chemistry operates at different scales
- Macroscopic Scale
The substances that are large enough to be visible to human eyes. In this scale we do not require the help of optical instruments to provide a magnified view. Properties like boiling and melting points, latent heat of evaporation, entropy of fusion or coefficient of linear thermal expansion can be dealt with on a macroscopic scale. For example water. In this scale we deal with physical state of water like solid, liquid or gaseous but don't deal with chemistry of H2O molecule.
- Microscopic Scale
Microscopic scale deals with the substance which is visible to human eyes with the help of optical instruments. Optical instruments help to magnify substances, for example microscopes. The study of crystal shape structures falls under this scale.
Microscopic Scale
- Atomic Scale
At Atomic scale properties of matter are different from element to element. The elements that show similar properties are grouped together in a periodic table. Physical chemistry properties like atomic mass and atomic number are studied in atomic scale. Bond lengths between the atoms are also studied at atomic scale by physical chemists.
Atomic Scale
- Subatomic Scale
Subatomic Scales involve the study of particles that are smaller than atomic particles, commonly referred as subatomic particles. Due to the dual nature of the particles at subatomic level it is sometimes referred to as waves or energy. This is the most advanced level in the study of physical chemistry and can have applications in the field of nuclear chemistry.
Read More: Group 15 Elements
Branches of Physical Chemistry
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The way in which physics is used to determine the chemical reaction and solve the important problems in chemistry makes it important for physical chemistry. Physical chemistry is the diverse branch of chemistry based on the type of study and scales it is divided into various different disciplines.
- Spectroscopy: It is a physical chemistry branch which studies the interaction between matter and electromagnetic radiation.
- Quantum Chemistry: Movement of nuclei and study of strength and shapes of chemical bond are under quantum chemistry.
- Chemical Kinetics: Rate and feasibility of chemical reaction are studied under this topic. Other than that the presence of catalyst or concentration can be other factors for rate of reaction are also studied under Chemical kinetics.
Things to Remember
- Physical chemistry involves the study of atoms, subatomic particles, and molecules.
- Physical chemistry deals with interactions and changes in materials.
- It uses physics principles and complex mathematics to determine the chemical reaction and properties.
- It studies behavior of matter at atomic or molecular level or even at subatomic level.
- Sub Branches: Spectroscopy, chemical thermodynamics, Quantum chemistry, Chemical kinetics.
Sample Questions
Ques: What is Physical Chemistry? (2 Marks)
Ans: Physical chemistry is the branch of chemistry which deals with the study of particulate events in the chemical system with the help of physics principles, techniques and mathematics. It uses ideas such as motion, force, time, thermodynamics, statisal mechanism, quantum chemistry and chemical equilibrium.
Ques:Where is physical chemistry used? (2 Marks)
Ans: Physical chemistry provides a wide education and prepares scientists for scientific careers. Mathematical rigour of physical chemistry is used in Material Science and Molecular modelling. Physical chemistry is also used in analytical chemistry. In this application it helps to improve and develop analytical procedures.
Ques: What is Quantum Physics? (2 Marks)
Ans: Quantum physics is defined as the study of physics on a microscopic level. It is basically based on movement of atoms and molecules. Because of Quantum Physics we are able to determine the nature of the particle, matter created by the particles, and also the force between them that they hold on to each other.
Ques: Quantum Physics relay on three forces, what are these three forces? (2 Marks)
Ans: In quantum physics theories and fundamental forces there are three forces the which are most important in terms of quantum physics:
- The force between the atoms holding each other together is Electromagnetic force.
- Stable nucleus at the centre of the atoms explains the strong nuclear force among them.
- Atoms undergoing radioactive decay can be explained by weak nuclear force.
Ques: What is Atomic Spectrum? Give types of Atomic Spectrum? (2 Marks)
Ans: Atomic Spectrum is defined as the electromagnetic radiation that is absorbed or emitted by electrons when there is transition between different energy levels within an atom.
There are three types of Atomic Spectrum as follows:
- Adsorption Spectra
- Emission Spectra
- Continuous spectra
Ques: What causes Atomic Spectrum? Give uses of Atomic spectrum? (2 Marks)
Ans: Atomic spectrum is caused when electrons get excited from one energy level to another. When in an excited state, it either absorbs or emits light of specific wavelength.
These are the uses of Atomic Spectrum as follows:
- It is used in metallurgy to identify specific lines of materials.
- It is used in Pharmaceuticals industries to find the traces of materials used.
- It is used to study multidimensional elements.
Ques: What is Chemical Kinetics? (2 Marks)
Ans: Chemical kinetics is the branch of physical chemistry. It deals with understanding the rate of chemical reactions. It works together with thermodynamics, which deals with the direction in which a process occurs but only tells us the rate of reaction. This study helps us to understand the chemical reaction mechanism and its characteristics.
Ques: What is electrochemistry? (2 Marks)
Ans: Electrochemistry is the branch of chemistry which deals with the relations between chemical reaction and electricity. Spontaneously occurring chemical energy produces electric energy and these electric energy. These reactions are used in batteries and fuel cells to generate electricity. On the other hand, electric energy can be used in chemical reactions to occur spontaneously.
Ques: What is chemical thermodynamics? (2 Marks)
Ans: Chemical thermodynamics is the branch of Physical chemistry which studies how heat and work are related to each other in chemical reactions and change in state. Chemical Thermodynamics is the bridge between the individual properties and the microscopic properties of its constituent molecules and atoms.
Ques: What are the laws of thermodynamics? (2 Marks)
Ans: The three laws of thermodynamics are as follows:
- First law of thermodynamics :- Law of conservation of Energy, the state that energy cannot be created or destroyed in an isolated system.
- Second Law of Thermodynamics:- Entropy of any isolated system always increases.
- Third Law of Thermodynamics:- The entropy of the system approaches a constant value as the temperature approaches absolute zero.
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