Chapter 4 Atomic physics & Spectra

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Absorption Line
An isolated bright or dark line in a spectrum produced by emission or absorption of light of a single wavelength.
Absorption Line Spectrum
The electromagnetic spectrum, broken by a specific pattern of dark lines or bands, observed when radiation traverses a particular absorbing medium. The absorption pattern is unique and can be used to identify the material.
is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons.
Atomic Number
is the number of protons found in the nucleus of an atom and therefore identical to the charge number of the nucleus
is an idealized physical body that absorbs all incident electromagnetic radiation, regardless of frequency or angle of incidence.
Blackbody Curve
is the type of electromagnetic radiation within or surrounding a body in thermodynamic equilibrium with its environment, or emitted by a black body (an opaque and non-reflective body) held at constant, uniform temperature. The radiation has a specific spectrum and intensity that depends only on the temperature of the body.
is any decrease in wavelength (increase in frequency); the opposite effect is referred to as redshift. In visible light, this shifts the color from the red end of the spectrum to the blue end. The term also applies when photons outside the visible spectrum
Continuous Spectrum
a continuous spectrum usually means a set of values for some physical quantity that is best described as an interval of real numbers
Diffraction Grating
is an optical component with a periodic structure, which splits and diffracts light into several beams travelling in different directions.
Electromagnetic Force
is one of the four fundamental interactions in nature, the other three being the strong interaction, the weak interaction, and gravitation.
is a subatomic particle with a negative elementary electric charge
is a pure chemical substance consisting of a single type of atom distinguished by its atomic number, which is the number of protons in its atomic nucleus
Emission Line
The emission spectrum of a chemical element or chemical compound is the spectrum of frequencies of electromagnetic radiation emitted due to an atom’s electrons making a transition from a high energy state to a lower energy state.
Emission Line Spectum
is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from a deficiency or excess of photons in a narrow frequency range, compared with the nearby frequencies.
Energy Flux
is the rate of transfer of energy through a surface.
Excited State
is an elevation in energy level above an arbitrary baseline energy state. In physics there is a specific technical definition for energy level which is often associated with an atom being excited to an excited state.
Ground State
of a quantum mechanical system is its lowest-energy state; the energy of the ground state is known as the zero-point energy of the system. An excited state is any state with energy greater than the ground state. The ground state of a quantum field theory is usually called the vacuum state or the vacuum.
is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving the atom a net positive or negative electrical charge.
is the process by which an atom or a molecule acquires a negative or positive charge by gaining or losing electrons. Ionization, often, results from the interaction of an atom or a molecule with an ionizing particle, including charged particles with sufficient energies and energetic photons.
are variants of a particular chemical element such that, while all isotopes of a given element have the same number of protons in each atom, they differ in neutron number.
Kirchhoff’s Laws
A hot solid object produces light with a continuous spectrum. Kirchhoff coined the term black-body radiation.
A hot tenuous gas produces light with spectral lines at discrete wavelengths which depend on the energy levels of the atoms in the gas.
A hot solid object surrounded by a cool tenuous gas produces light with an almost continuous spectrum which has gaps at discrete wavelengths depending on the energy levels of the atoms in the gas.
s generally understood as a measurement of brightness.
is an electrically neutral group of two or more atoms held together by chemical bonds.
is a subatomic hadron particle that has the symbol n or n0. Neutrons have no net electric charge and a mass slightly larger than that of a proton.
is the very dense region consisting of protons and neutrons at the center of an atom.
Peroplanck’s Lawodic Table
In 1863 there were 56 known elements with a new element being discovered at a rate of approximately one per year
Proper Motion
The proper motion of a star is its angular change in position over time as seen from the center of mass of the Solar System
Quantum Mechanics
is a branch of physics which deals with physical phenomena at microscopic scales, where the action is on the order of the Planck constant. It departs from classical mechanics primarily at the quantum realm of atomic and subatomic length scales.
Radial Velocity
is the velocity of an object in the direction of the radius
happens when light or other electromagnetic radiation from an object moving away from the observer is increased in wavelength, or shifted to the red end of the spectrum.
Spectral Analysis
Spectral Analysis
A spectrograph is an instrument that separates an incoming wave into a frequency spectrum. There are several kinds of machines referred to as spectrographs, depending on the precise nature of the waves. The term was first used in 1884.
is an instrument used to measure properties of light over a specific portion of the electromagnetic spectrum, typically used in spectroscopic analysis to identify materials.
Stefan-Boltzmann Law
also known as Stefan’s law, describes the power radiated from a black body in terms of its temperature.
Strong Nuclear Force
In particle physics, the strong interaction is one of the four fundamental interactions of nature, the others being electromagnetism, the weak interaction and gravitation.
Transition of an electron
is a change of an electron from one quantum state to another within an atom or artificial atom. It appears discontinuous as the electron “jumps” from one energy level to another in a few nanoseconds or less. It is also known as atomic transition, quantum jump, or quantum leap.
Transverse Velocity
is the rate of change of the position of an object, equivalent to a specification of its speed and direction of motion, 60 km/h to the north. Velocity is an important concept in kinematics, the branch of classical mechanics which describes the motion of bodies.
Weak Nuclear Force
the weak interaction is the mechanism responsible for the weak force or weak nuclear force, one of the four fundamental interactions of nature, alongside the strong interaction, electromagnetism, and gravitation. The theory of the weak interaction is sometimes called quantum flavordynamics in analogy with the terms QCD and QED, but in practice the term is rarely used because the weak force is best understood in terms of electro-weak theory
Wien’s Law
states that the wavelength distribution of thermal radiation from a black body at any temperature has essentially the same shape as the distribution at any other temperature, except that each wavelength is displaced on the graph.
Categories: Atomic Physics