Difference between chemistry and physics
Encyclopedia
Chemistry
and physics
are branches of science
that both study matter
. The difference in the two lies in the scope and in the approach. Consequently, chemists and physicists are trained differently, and they have different roles working in their profession, even when they work in a team. The division between chemistry and physics becomes diffuse at the interface of the two branches, notably in fields such as physical chemistry
, quantum mechanics
, nuclear physics
/chemistry
, spectroscopy
, solid state physics, crystallography
, and nanotechnology
.
, all of which are not observed under typical terrestrial conditions. Although fundamental laws that govern the behavior of matter apply both in chemistry and physics, the disciplines of physics and chemistry are distinct. Physics is concerned with nature from a very large scale (the entire universe) down to a very small scale (subatomic particles). All natural (or man-made) phenomena that are measurable follow some behavior that is in accordance with the most basic principles studied in physics. Physics is involved with the fundamental principles of physical phenomena and the basic forces of nature, and also gives insight into the aspects of space and time. Physics also deals with the basic principles that explain matter and energy, and may study aspects of atomic matter by following concepts derived from the most fundamental principles. Chemistry focuses on how substances interact with each other and with energy (for example heat and light). The study of change of matter (chemical reactions) and synthesis lies at the heart of chemistry, and gives rise to concepts such as organic functional groups and rate laws for chemical reactions. Chemistry also studies the properties of matter at larger scale (for example, astrochemistry
) and the reactions of matter at larger scale (for example, technical chemistry), but typically, explanations and predictions are related back to the underlying atomic structure, giving more emphasis on the methods for the identification of molecules and their mechanisms of transformation than any other science. Chemistry is not a sub-discipline of physics because chemistry differs from physics in aspects such as approach, emphasis (scope) and training of its practitioners. The knowledge obtained from studying either chemistry or physics can be used in a more direct way (as an applied science
) or can be used to further our understanding of some aspect of nature.
, for example, materials are characterized by their index of diffraction
, and materials with the same index of diffraction will have identical properties. Chemistry, on the other hand, focuses on what compounds are present in a sample, and explores how changing the structure of molecules will change their reactivity and their physical properties.
The two sciences differ in the role that theory plays within the discipline. Physics can be divided into experimental and theoretical physics
. Historically, theoretical physics has correctly predicted phenomena that were out of experimental reach at the time, and could be verified only after experimental techniques caught up. In chemistry, the role of theory historically has been a retrospective one, summarizing experimental data and predicting the outcome of similar experiments. However, with the increasing power of computational methods in chemistry, it has become possible to predict whether a hypothetical compound is stable or not before experimental data is available.
), students have to be familiar with differential equations. In a typical undergraduate program for chemistry majors, emphasis is placed on laboratory classes and understanding and applying models describing chemical bonds and molecular structure. Emphasis is also placed in the methods for analysis and the formulas and equations used when considering the chemical transformation. Students take courses in math, physics, chemistry and often biochemistry. Between the two programs of study, there is a large area of overlap (calculus
, introductory physics, quantum theory
, thermodynamics). However, physics places a larger emphasis on fundamental theory (with its deep mathematical treatment) while chemistry places more emphasis in combining the most important mathematical definitions of the theory with the approach of the molecular models. Laboratory skills may differ in both programs, as students may be involved in different technologies, depending on the program and the institution of higher education (for example, a chemistry student may spend more laboratory time dealing with glassware for distillation and purification or on a form of chromatography
-spectroscopy
instrument, while a physics student may spend much more time dealing with a laser and non-linear optics technology or some complex electrical circuit).
Chemistry
Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds....
and physics
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...
are branches of science
Science
Science is a systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the universe...
that both study matter
Matter
Matter is a general term for the substance of which all physical objects consist. Typically, matter includes atoms and other particles which have mass. A common way of defining matter is as anything that has mass and occupies volume...
. The difference in the two lies in the scope and in the approach. Consequently, chemists and physicists are trained differently, and they have different roles working in their profession, even when they work in a team. The division between chemistry and physics becomes diffuse at the interface of the two branches, notably in fields such as physical chemistry
Physical chemistry
Physical chemistry is the study of macroscopic, atomic, subatomic, and particulate phenomena in chemical systems in terms of physical laws and concepts...
, quantum mechanics
Quantum mechanics
Quantum mechanics, also known as quantum physics or quantum theory, is a branch of physics providing a mathematical description of much of the dual particle-like and wave-like behavior and interactions of energy and matter. It departs from classical mechanics primarily at the atomic and subatomic...
, nuclear physics
Nuclear physics
Nuclear physics is the field of physics that studies the building blocks and interactions of atomic nuclei. The most commonly known applications of nuclear physics are nuclear power generation and nuclear weapons technology, but the research has provided application in many fields, including those...
/chemistry
Nuclear chemistry
Nuclear chemistry is the subfield of chemistry dealing with radioactivity, nuclear processes and nuclear properties.It is the chemistry of radioactive elements such as the actinides, radium and radon together with the chemistry associated with equipment which are designed to perform nuclear...
, spectroscopy
Spectroscopy
Spectroscopy is the study of the interaction between matter and radiated energy. Historically, spectroscopy originated through the study of visible light dispersed according to its wavelength, e.g., by a prism. Later the concept was expanded greatly to comprise any interaction with radiative...
, solid state physics, crystallography
Crystallography
Crystallography is the experimental science of the arrangement of atoms in solids. The word "crystallography" derives from the Greek words crystallon = cold drop / frozen drop, with its meaning extending to all solids with some degree of transparency, and grapho = write.Before the development of...
, and nanotechnology
Nanotechnology
Nanotechnology is the study of manipulating matter on an atomic and molecular scale. Generally, nanotechnology deals with developing materials, devices, or other structures possessing at least one dimension sized from 1 to 100 nanometres...
.
Scope
Physics and chemistry are sciences that may overlap when the system under study involves matter we commonly encounter on earth, composed of electrons and nuclei made of protons and neutrons. On the other hand, chemistry is not concerned with other forms of matter such as quarks, mu and tau mesons and dark matterDark matter
In astronomy and cosmology, dark matter is matter that neither emits nor scatters light or other electromagnetic radiation, and so cannot be directly detected via optical or radio astronomy...
, all of which are not observed under typical terrestrial conditions. Although fundamental laws that govern the behavior of matter apply both in chemistry and physics, the disciplines of physics and chemistry are distinct. Physics is concerned with nature from a very large scale (the entire universe) down to a very small scale (subatomic particles). All natural (or man-made) phenomena that are measurable follow some behavior that is in accordance with the most basic principles studied in physics. Physics is involved with the fundamental principles of physical phenomena and the basic forces of nature, and also gives insight into the aspects of space and time. Physics also deals with the basic principles that explain matter and energy, and may study aspects of atomic matter by following concepts derived from the most fundamental principles. Chemistry focuses on how substances interact with each other and with energy (for example heat and light). The study of change of matter (chemical reactions) and synthesis lies at the heart of chemistry, and gives rise to concepts such as organic functional groups and rate laws for chemical reactions. Chemistry also studies the properties of matter at larger scale (for example, astrochemistry
Astrochemistry
Astrochemistry is the study of the abundance and reactions of chemical elements and molecules in the universe, and their interaction with radiation. The discipline is an overlap of astronomy and chemistry. The word "astrochemistry" may be applied to both the Solar System and the interstellar medium...
) and the reactions of matter at larger scale (for example, technical chemistry), but typically, explanations and predictions are related back to the underlying atomic structure, giving more emphasis on the methods for the identification of molecules and their mechanisms of transformation than any other science. Chemistry is not a sub-discipline of physics because chemistry differs from physics in aspects such as approach, emphasis (scope) and training of its practitioners. The knowledge obtained from studying either chemistry or physics can be used in a more direct way (as an applied science
Applied science
Applied science is the application of scientific knowledge transferred into a physical environment. Examples include testing a theoretical model through the use of formal science or solving a practical problem through the use of natural science....
) or can be used to further our understanding of some aspect of nature.
Approach
Although both physics and chemistry are concerned with matter and its interaction with energy, the two disciplines differ in approach. In physics, it is typical to abstract from the specific type of matter, and to focus on the common properties of many different materials. In opticsOptics
Optics is the branch of physics which involves the behavior and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behavior of visible, ultraviolet, and infrared light...
, for example, materials are characterized by their index of diffraction
Diffraction
Diffraction refers to various phenomena which occur when a wave encounters an obstacle. Italian scientist Francesco Maria Grimaldi coined the word "diffraction" and was the first to record accurate observations of the phenomenon in 1665...
, and materials with the same index of diffraction will have identical properties. Chemistry, on the other hand, focuses on what compounds are present in a sample, and explores how changing the structure of molecules will change their reactivity and their physical properties.
The two sciences differ in the role that theory plays within the discipline. Physics can be divided into experimental and theoretical physics
Theoretical physics
Theoretical physics is a branch of physics which employs mathematical models and abstractions of physics to rationalize, explain and predict natural phenomena...
. Historically, theoretical physics has correctly predicted phenomena that were out of experimental reach at the time, and could be verified only after experimental techniques caught up. In chemistry, the role of theory historically has been a retrospective one, summarizing experimental data and predicting the outcome of similar experiments. However, with the increasing power of computational methods in chemistry, it has become possible to predict whether a hypothetical compound is stable or not before experimental data is available.
Training
In a typical undergraduate program for physics majors, required courses are in the sub-disciplines of physics, with additional required courses in mathematics. Because much of the insight of physics is described by differential equations relating matter, space and time (for example Newton's law of motion and the Maxwell equations of electromagnetismElectromagnetism
Electromagnetism is one of the four fundamental interactions in nature. The other three are the strong interaction, the weak interaction and gravitation...
), students have to be familiar with differential equations. In a typical undergraduate program for chemistry majors, emphasis is placed on laboratory classes and understanding and applying models describing chemical bonds and molecular structure. Emphasis is also placed in the methods for analysis and the formulas and equations used when considering the chemical transformation. Students take courses in math, physics, chemistry and often biochemistry. Between the two programs of study, there is a large area of overlap (calculus
Calculus
Calculus is a branch of mathematics focused on limits, functions, derivatives, integrals, and infinite series. This subject constitutes a major part of modern mathematics education. It has two major branches, differential calculus and integral calculus, which are related by the fundamental theorem...
, introductory physics, quantum theory
Quantum theory
Quantum theory may mean:In science:*Quantum mechanics: a subset of quantum physics explaining the physical behaviours at atomic and sub-atomic levels*Old quantum theory under the Bohr model...
, thermodynamics). However, physics places a larger emphasis on fundamental theory (with its deep mathematical treatment) while chemistry places more emphasis in combining the most important mathematical definitions of the theory with the approach of the molecular models. Laboratory skills may differ in both programs, as students may be involved in different technologies, depending on the program and the institution of higher education (for example, a chemistry student may spend more laboratory time dealing with glassware for distillation and purification or on a form of chromatography
Chromatography
Chromatography is the collective term for a set of laboratory techniques for the separation of mixtures....
-spectroscopy
Spectroscopy
Spectroscopy is the study of the interaction between matter and radiated energy. Historically, spectroscopy originated through the study of visible light dispersed according to its wavelength, e.g., by a prism. Later the concept was expanded greatly to comprise any interaction with radiative...
instrument, while a physics student may spend much more time dealing with a laser and non-linear optics technology or some complex electrical circuit).
Careers in chemistry and physics
According to Bureau of Labor Statistics (United States Department of Labor), there are 80,000 chemists and 17,000 physicists working in the United States as of May 2010. In addition, 21,000 chemists and 13,500 physicists teach in high school. Chemistry is the only science that has an entire industry, the chemical industry, named after it, and many chemists work in this industry, in research and development, production, training or management. Other industries employing chemists include the petroleum, pharmaceutical and food industry. While there is no industry named after physics, many industries have grown out of physics research, most notably the semiconductor and electronics industry. Physicists are also employed outside of science, for example in finance, because of their training in modeling complex systems.Topics at the interface of chemistry and physics
Chemistry and physics are not strictly separated sciences, and chemists and physicists work in interdisciplinary teams to explore the following topics.- Quantum chemistryQuantum chemistryQuantum chemistry is a branch of chemistry whose primary focus is the application of quantum mechanics in physical models and experiments of chemical systems...
- Spectroscopy
- ThermodynamicsThermodynamicsThermodynamics is a physical science that studies the effects on material bodies, and on radiation in regions of space, of transfer of heat and of work done on or by the bodies or radiation...
- Solid state physics
- Crystallography
- NanomaterialsNanomaterialsNanomaterials is a field that takes a materials science-based approach to nanotechnology. It studies materials with morphological features on the nanoscale, and especially those that have special properties stemming from their nanoscale dimensions...