CHM 2045C: Key Terms Chapter 7: Atomic Structure


Amplitude:  the maximum height of a wave from its axis of propagation


Angular momentum quantum number (l):  an integer value from zero up to n -1, this quantum number indicates the type of subshell the electron is in


Balmer series:  the visible portion of the line emission spectrum of hydrogen; these lines correspond to the electron in hydrogen moving from higher energy levels down to the second energy level


Electromagnetic radiation:  radiation that consist of electric and magnetic fields in space, including light, microwaves, radio signals and x-rays


Excited state:  an atom is in an excited state if any of its electrons are in a higher energy level than in the ground state


Frequency:  the number of waves that pass a given point in some unit of time.  Frequency is abbreviated by the Greek letter nu (v)


Ground state:  an atom is in its ground state if all of its electrons are in the lowest possible energy levels


Heisenberg uncertainty principle:  we cannot know the exact position and the exact energy of an object at the same time; there must be a minimum uncertainty present


Line emission spectrum:  when the atoms of an element in the gas phase are excited, they emit electromagnetic radiation having only particular energies.  When this light is passed through a prism, instead of getting a continuous spectrum we obtain only certain lines in the spectrum


Lyman series:  a series of emission lines in the spectrum of hydrogen which fall in the ultraviolet region; these lines correspond to transitions of the electron in hydrogen from higher energy level


Magnetic quantum number (m1):  -1 up to +1, this quantum number indicates the orbital in a given subshell that the electron is in


Nodal surface: in an orbital, a surface (often a plane) along which there is zero probability of finding


Node:  a point on wave that has zero amplitude


Orbital:  a region of space in which we are likely to find and electron; each orbital corresponds to an allowed energy state of an electron in an atom or molecule



Photoelectric effect:  a phenomenon explained by Albert Einstein through assuming that electromagnetic radiation is quantized.  The phenomenon involved the emission of electrons by metals.  If light below a certain frequency is used, then no electrons are emitted, regardless the intensity of the light.  Once a certain frequency is reached, the metal emits electrons, and the number of electrons emitted increases with increasing intensity of the light


Principal quantum number (n):  an integer value from one on up, this quantum number indicates the energy level (shell) of the electron


Quantized:  something is said to be quantized if it can have only particular values


Quantum mechanics:  also called wave mechanics, an approach to atomic behavior that describes the electron as being a wave.  In this model of the electron, the energies of the electron are quantized


Quantum numbers:  a set of numbers that define the properties of an atomic orbital or identifies the spin state of an electron in the orbital


Ryberg equation:  an equation that predicts the wavelength of the lines in the emission spectrum of hydrogen


Wave function:  an equation, symbolized by the Greek letter φ, which characterizes the electron as a wave and whose solutions give the energies of the electron


Wavelength:  the distance between one point on a wave and its repeat on the next waveform (for example, from one crest to the next crest).  Wavelength is abbreviated by the Greek letter lambda (λ)