A report on Atom and Photon

Atoms and molecules as depicted in John Dalton's A New System of Chemical Philosophy vol. 1 (1808)
Photons are emitted by a cyan laser beam outside, orange laser beam inside calcite and its fluorescence
The Geiger–Marsden experiment:
Left: Expected results: alpha particles passing through the plum pudding model of the atom with negligible deflection.
Right: Observed results: a small portion of the particles were deflected by the concentrated positive charge of the nucleus.
Photoelectric effect: the emission of electrons from a metal plate caused by light quanta – photons.
The Bohr model of the atom, with an electron making instantaneous "quantum leaps" from one orbit to another with gain or loss of energy. This model of electrons in orbits is obsolete.
The cone shows possible values of wave 4-vector of a photon. The "time" axis gives the angular frequency (rad⋅s−1) and the "space" axis represents the angular wavenumber (rad⋅m−1). Green and indigo represent left and right polarization
The binding energy needed for a nucleon to escape the nucleus, for various isotopes
Thomas Young's double-slit experiment in 1801 showed that light can act as a wave, helping to invalidate early particle theories of light.
A potential well, showing, according to classical mechanics, the minimum energy V(x) needed to reach each position x. Classically, a particle with energy E is constrained to a range of positions between x1 and x2.
In 1900, Maxwell's theoretical model of light as oscillating electric and magnetic fields seemed complete. However, several observations could not be explained by any wave model of electromagnetic radiation, leading to the idea that light-energy was packaged into quanta described by . Later experiments showed that these light-quanta also carry momentum and, thus, can be considered particles: The photon concept was born, leading to a deeper understanding of the electric and magnetic fields themselves.
3D views of some hydrogen-like atomic orbitals showing probability density and phase (g orbitals and higher are not shown)
Up to 1923, most physicists were reluctant to accept that light itself was quantized. Instead, they tried to explain photon behaviour by quantizing only matter, as in the Bohr model of the hydrogen atom (shown here). Even though these semiclassical models were only a first approximation, they were accurate for simple systems and they led to quantum mechanics.
This diagram shows the half-life (T½) of various isotopes with Z protons and N neutrons.
Photons in a Mach–Zehnder interferometer exhibit wave-like interference and particle-like detection at single-photon detectors.
These electron's energy levels (not to scale) are sufficient for ground states of atoms up to cadmium (5s2 4d10) inclusively. Do not forget that even the top of the diagram is lower than an unbound electron state.
Stimulated emission (in which photons "clone" themselves) was predicted by Einstein in his kinetic analysis, and led to the development of the laser. Einstein's derivation inspired further developments in the quantum treatment of light, which led to the statistical interpretation of quantum mechanics.
An example of absorption lines in a spectrum
Different electromagnetic modes (such as those depicted here) can be treated as independent simple harmonic oscillators. A photon corresponds to a unit of energy E = hν in its electromagnetic mode.
Graphic illustrating the formation of a Bose–Einstein condensate
Scanning tunneling microscope image showing the individual atoms making up this gold (100) surface. The surface atoms deviate from the bulk crystal structure and arrange in columns several atoms wide with pits between them (See surface reconstruction).
Periodic table showing the origin of each element. Elements from carbon up to sulfur may be made in small stars by the alpha process. Elements beyond iron are made in large stars with slow neutron capture (s-process). Elements heavier than iron may be made in neutron star mergers or supernovae after the r-process.

During a molecular, atomic or nuclear transition to a lower energy level, photons of various energy will be emitted, ranging from radio waves to gamma rays.

- Photon

The electron can change its state to a higher energy level by absorbing a photon with sufficient energy to boost it into the new quantum state.

- Atom
Atoms and molecules as depicted in John Dalton's A New System of Chemical Philosophy vol. 1 (1808)

19 related topics with Alpha

Overall

Wave functions of the electron in a hydrogen atom at different energy levels. Quantum mechanics cannot predict the exact location of a particle in space, only the probability of finding it at different locations. The brighter areas represent a higher probability of finding the electron.

Quantum mechanics

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Wave functions of the electron in a hydrogen atom at different energy levels. Quantum mechanics cannot predict the exact location of a particle in space, only the probability of finding it at different locations. The brighter areas represent a higher probability of finding the electron.
Fig. 1
Position space probability density of a Gaussian wave packet moving in one dimension in free space.
1-dimensional potential energy box (or infinite potential well)
Some trajectories of a harmonic oscillator (i.e. a ball attached to a spring) in classical mechanics (A-B) and quantum mechanics (C-H). In quantum mechanics, the position of the ball is represented by a wave (called the wave function), with the real part shown in blue and the imaginary part shown in red. Some of the trajectories (such as C, D, E, and F) are standing waves (or "stationary states"). Each standing-wave frequency is proportional to a possible energy level of the oscillator. This "energy quantization" does not occur in classical physics, where the oscillator can have any energy.
Schematic of a Mach–Zehnder interferometer.
Max Planck is considered the father of the quantum theory.
The 1927 Solvay Conference in Brussels was the fifth world physics conference.

Quantum mechanics is a fundamental theory in physics that provides a description of the physical properties of nature at the scale of atoms and subatomic particles.

Furthermore, versions of the experiment that include detectors at the slits find that each detected photon passes through one slit (as would a classical particle), and not through both slits (as would a wave).

Hydrogen atomic orbitals at different energy levels. The more opaque areas are where one is most likely to find an electron at any given time.

Electron

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Subatomic particle whose electric charge is negative one elementary charge.

Subatomic particle whose electric charge is negative one elementary charge.

Hydrogen atomic orbitals at different energy levels. The more opaque areas are where one is most likely to find an electron at any given time.
A beam of electrons deflected in a circle by a magnetic field
J. J. Thomson
Robert Millikan
The Bohr model of the atom, showing states of an electron with energy quantized by the number n. An electron dropping to a lower orbit emits a photon equal to the energy difference between the orbits.
In quantum mechanics, the behavior of an electron in an atom is described by an orbital, which is a probability distribution rather than an orbit. In the figure, the shading indicates the relative probability to "find" the electron, having the energy corresponding to the given quantum numbers, at that point.
Standard Model of elementary particles. The electron (symbol e) is on the left.
Example of an antisymmetric wave function for a quantum state of two identical fermions in a 1-dimensional box. If the particles swap position, the wave function inverts its sign.
A schematic depiction of virtual electron–positron pairs appearing at random near an electron (at lower left)
A particle with charge q (at left) is moving with velocity v through a magnetic field B that is oriented toward the viewer. For an electron, q is negative so it follows a curved trajectory toward the top.
Here, Bremsstrahlung is produced by an electron e deflected by the electric field of an atomic nucleus. The energy change E2 − E1 determines the frequency f of the emitted photon.
Probability densities for the first few hydrogen atom orbitals, seen in cross-section. The energy level of a bound electron determines the orbital it occupies, and the color reflects the probability of finding the electron at a given position.
A lightning discharge consists primarily of a flow of electrons. The electric potential needed for lightning can be generated by a triboelectric effect.
Lorentz factor as a function of velocity. It starts at value 1 and goes to infinity as v approaches c.
Pair production of an electron and positron, caused by the close approach of a photon with an atomic nucleus. The lightning symbol represents an exchange of a virtual photon, thus an electric force acts. The angle between the particles is very small.
An extended air shower generated by an energetic cosmic ray striking the Earth's atmosphere
Aurorae are mostly caused by energetic electrons precipitating into the atmosphere.
During a NASA wind tunnel test, a model of the Space Shuttle is targeted by a beam of electrons, simulating the effect of ionizing gases during re-entry.

Electrons radiate or absorb energy in the form of photons when they are accelerated.

The Coulomb force interaction between the positive protons within atomic nuclei and the negative electrons without, allows the composition of the two known as atoms.

Einstein in 1921, by Ferdinand Schmutzer

Albert Einstein

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German-born theoretical physicist, widely acknowledged to be one of the greatest and most influential physicists of all time.

German-born theoretical physicist, widely acknowledged to be one of the greatest and most influential physicists of all time.

Einstein in 1921, by Ferdinand Schmutzer
Einstein at the age of three in 1882
Albert Einstein in 1893 (age 14)
Einstein's Matura certificate, 1896
Albert Einstein and Mileva Marić Einstein, 1912
Einstein in 1904 (age 25)
Olympia Academy founders: Conrad Habicht, Maurice Solovine and Albert Einstein
The New York Times reported confirmation of "the Einstein theory" (specifically, the bending of light by gravitation) based on 29 May 1919 eclipse observations in Principe (Africa) and Sobral (Brazil), after the findings were presented on 6 November 1919 to a joint meeting in London of the Royal Society and the Royal Astronomical Society. (Full text)
Einstein with his second wife, Elsa, in 1921
Einstein's official portrait after receiving the 1921 Nobel Prize in Physics
Albert Einstein at a session of the International Committee on Intellectual Cooperation (League of Nations) of which he was a member from 1922 to 1932.
Albert Einstein (left) and Charlie Chaplin at the Hollywood premiere of City Lights, January 1931
Cartoon of Einstein after shedding his "pacifism" wings (Charles R. Macauley, c. 1933)
Albert Einstein's landing card (26 May 1933), when he landed in Dover (United Kingdom) from Ostend (Belgium) to visit Oxford.
Portrait of Einstein taken in 1935 at Princeton
Einstein accepting US citizenship certificate from judge Phillip Forman
Einstein in 1947
Albert Einstein (right) with writer, musician and Nobel laureate Rabindranath Tagore, 1930
Albert Einstein with his wife Elsa Einstein and Zionist leaders, including future President of Israel Chaim Weizmann, his wife Vera Weizmann, Menahem Ussishkin, and Ben-Zion Mossinson on arrival in New York City in 1921
Eddington's photograph of a solar eclipse
Einstein with Millikan and Georges Lemaître at the California Institute of Technology in January 1933.
Einstein at his office, University of Berlin, 1920
The photoelectric effect. Incoming photons on the left strike a metal plate (bottom), and eject electrons, depicted as flying off to the right.
Einstein during his visit to the United States
Newspaper headline on 4 May 1935
Einstein and Niels Bohr, 1925
The 1927 Solvay Conference in Brussels, a gathering of the world's top physicists. Einstein is in the center.
Einstein (second from left) at a picnic in Oslo during the visit to Denmark and Norway in 1920. Heinrich Goldschmidt (left), Ole Colbjørnsen (seated in center) and Jørgen Vogt behind Ilse Einstein.

He also investigated the thermal properties of light and the quantum theory of radiation, which laid the foundation of the photon theory of light.

Two papers he published in 1902–1903 (thermodynamics) attempted to interpret atomic phenomena from a statistical point of view.

Electric field of a positive and a negative point charge

Electric charge

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Physical property of matter that causes charged matter to experience a force when placed in an electromagnetic field.

Physical property of matter that causes charged matter to experience a force when placed in an electromagnetic field.

Electric field of a positive and a negative point charge
Diagram showing field lines and equipotentials around an electron, a negatively charged particle. In an electrically neutral atom, the number of electrons is equal to the number of protons (which are positively charged), resulting in a net zero overall charge
Coulomb's torsion balance

In ordinary matter, negative charge is carried by electrons, and positive charge is carried by the protons in the nuclei of atoms.

The study of photon-mediated interactions among charged particles is called quantum electrodynamics.

Elementary particle

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Elementary particle or fundamental particle is a subatomic particle that is not composed of other particles.

Elementary particle or fundamental particle is a subatomic particle that is not composed of other particles.

Ordinary matter is composed of atoms, once presumed to be elementary particles – atomos meaning "unable to be cut" in Greek – although the atom's existence remained controversial until about 1905, as some leading physicists regarded molecules as mathematical illusions, and matter as ultimately composed of energy.

Subatomic constituents of the atom were first identified in the early 1930s; the electron and the proton, along with the photon, the particle of electromagnetic radiation.

Hydrogen's purple glow in its plasma state, the most abundant in the universe

Matter

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Any substance that has mass and takes up space by having volume.

Any substance that has mass and takes up space by having volume.

Hydrogen's purple glow in its plasma state, the most abundant in the universe
Under the "quarks and leptons" definition, the elementary and composite particles made of the quarks (in purple) and leptons (in green) would be matter—while the gauge bosons (in red) would not be matter. However, interaction energy inherent to composite particles (for example, gluons involved in neutrons and protons) contribute to the mass of ordinary matter.
Quark structure of a proton: 2 up quarks and 1 down quark.
A comparison between the white dwarf IK Pegasi B (center), its A-class companion IK Pegasi A (left) and the Sun (right). This white dwarf has a surface temperature of 35,500 K.
Phase diagram for a typical substance at a fixed volume. Vertical axis is Pressure, horizontal axis is Temperature. The green line marks the freezing point (above the green line is solid, below it is liquid) and the blue line the boiling point (above it is liquid and below it is gas). So, for example, at higher T, a higher P is necessary to maintain the substance in liquid phase. At the triple point the three phases; liquid, gas and solid; can coexist. Above the critical point there is no detectable difference between the phases. The dotted line shows the anomalous behavior of water: ice melts at constant temperature with increasing pressure.
Galaxy rotation curve for the Milky Way. Vertical axis is speed of rotation about the galactic center. Horizontal axis is distance from the galactic center. The sun is marked with a yellow ball. The observed curve of speed of rotation is blue. The predicted curve based upon stellar mass and gas in the Milky Way is red. The difference is due to dark matter or perhaps a modification of the law of gravity. Scatter in observations is indicated roughly by gray bars.

All everyday objects that can be touched are ultimately composed of atoms, which are made up of interacting subatomic particles, and in everyday as well as scientific usage, "matter" generally includes atoms and anything made up of them, and any particles (or combination of particles) that act as if they have both rest mass and volume.

However it does not include massless particles such as photons, or other energy phenomena or waves such as light or heat.

Thomas Young's sketch of two-slit diffraction of waves, 1803

Wave–particle duality

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Concept in quantum mechanics that every particle or quantum entity may be described as either a particle or a wave.

Concept in quantum mechanics that every particle or quantum entity may be described as either a particle or a wave.

Thomas Young's sketch of two-slit diffraction of waves, 1803
The photoelectric effect. Incoming photons on the left strike a metal plate (bottom), and eject electrons, depicted as flying off to the right.
Propagation of de Broglie waves in 1d—real part of the complex amplitude is blue, imaginary part is green. The probability (shown as the colour opacity) of finding the particle at a given point x is spread out like a waveform; there is no definite position of the particle. As the amplitude increases above zero the curvature decreases, so the amplitude decreases again, and vice versa—the result is an alternating amplitude: a wave. Top: Plane wave. Bottom: Wave packet.
Couder experiments, "materializing" the pilot wave model
Particle impacts make visible the interference pattern of waves.
A quantum particle is represented by a wave packet.
Interference of a quantum particle with itself.

This phenomenon has been verified not only for elementary particles, but also for compound particles like atoms and even molecules.

Einstein's "light quanta" would not be called photons until 1925, but even in 1905 they represented the quintessential example of wave–particle duality.

An oil painting of a chemist (Ana Kansky, painted by Henrika Šantel in 1932)

Chemistry

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Scientific study of the properties and behavior of matter.

Scientific study of the properties and behavior of matter.

An oil painting of a chemist (Ana Kansky, painted by Henrika Šantel in 1932)
Laboratory, Institute of Biochemistry, University of Cologne in Germany.
Solutions of substances in reagent bottles, including ammonium hydroxide and nitric acid, illuminated in different colors
A diagram of an atom based on the Bohr model
Standard form of the periodic table of chemical elements. The colors represent different categories of elements
Carbon dioxide (CO2), an example of a chemical compound
A ball-and-stick representation of the caffeine molecule (C8H10N4O2).
A 2-D structural formula of a benzene molecule (C6H6)
Diagram showing relationships among the phases and the terms used to describe phase changes.
An animation of the process of ionic bonding between sodium (Na) and chlorine (Cl) to form sodium chloride, or common table salt. Ionic bonding involves one atom taking valence electrons from another (as opposed to sharing, which occurs in covalent bonding)
In the methane molecule (CH4), the carbon atom shares a pair of valence electrons with each of the four hydrogen atoms. Thus, the octet rule is satisfied for C-atom (it has eight electrons in its valence shell) and the duet rule is satisfied for the H-atoms (they have two electrons in their valence shells).
Emission spectrum of iron
During chemical reactions, bonds between atoms break and form, resulting in different substances with different properties. In a blast furnace, iron oxide, a compound, reacts with carbon monoxide to form iron, one of the chemical elements, and carbon dioxide.
The crystal lattice structure of potassium chloride (KCl), a salt which is formed due to the attraction of K+ cations and Cl− anions. Note how the overall charge of the ionic compound is zero.
Hydrogen bromide exists in the gas phase as a diatomic molecule
Democritus' atomist philosophy was later adopted by Epicurus (341–270 BCE).
15th-century artistic impression of Jābir ibn Hayyān (Geber), a Perso-Arab alchemist and pioneer in organic chemistry.
Antoine-Laurent de Lavoisier is considered the "Father of Modern Chemistry".
In his periodic table, Dmitri Mendeleev predicted the existence of 7 new elements, and placed all 60 elements known at the time in their correct places.
Top: Expected results: alpha particles passing through the plum pudding model of the atom undisturbed. 
Bottom: Observed results: a small portion of the particles were deflected, indicating a small, concentrated charge.

It is a natural science that covers the elements that make up matter to the compounds composed of atoms, molecules and ions: their composition, structure, properties, behavior and the changes they undergo during a reaction with other substances.

The particles that make up matter have rest mass as well – not all particles have rest mass, such as the photon.

Bohr in 1922

Niels Bohr

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Bohr in 1922
Bohr as a young man
Bohr and Margrethe Nørlund on their engagement in 1910.
The Bohr model of the hydrogen atom. A negatively charged electron, confined to an atomic orbital, orbits a small, positively charged nucleus; a quantum jump between orbits is accompanied by an emitted or absorbed amount of electromagnetic radiation.
The evolution of atomic models in the 20th century: Thomson, Rutherford, Bohr, Heisenberg/Schrödinger
The Niels Bohr Institute, part of the University of Copenhagen
Bohr and Albert Einstein (image from 1925) had a long-running debate about the metaphysical implication of quantum physics.
Werner Heisenberg (left) with Bohr at the Copenhagen Conference in 1934
Bohr with James Franck, Albert Einstein and Isidor Isaac Rabi (LR)
Bohr's coat of arms, 1947. Argent, a taijitu (yin-yang symbol) Gules and Sable. Motto: Contraria sunt complementa ("opposites are complementary").
The Theory of Spectra and Atomic Constitution (Drei Aufsätze über Spektren und Atombau), 1922

Niels Henrik David Bohr (7 October 1885 – 18 November 1962) was a Danish physicist who made foundational contributions to understanding atomic structure and quantum theory, for which he received the Nobel Prize in Physics in 1922.

The discovery of Compton scattering by Arthur Holly Compton in 1923 convinced most physicists that light was composed of photons, and that energy and momentum were conserved in collisions between electrons and photons.

A composite particle proton is made of two up quark and one down quark, which are elementary particles

Subatomic particle

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A composite particle proton is made of two up quark and one down quark, which are elementary particles
The Standard Model classification of particles

In physical sciences, a subatomic particle is a particle that composes an atom.

According to the Standard Model of particle physics, a subatomic particle can be either a composite particle, which is composed of other particles (for example, a proton, neutron, or meson), or an elementary particle, which is not composed of other particles (for example, an electron, photon, or muon).