electromagnetic radiation
radiant energy that exhibits wavelike behaviour and travels through space at the speed of light in a vacuum
wavelength
the distance between two consecutive peaks or troughs in a wave
frequency
the number of waves (cycles) per second that pass a given point in space
Planck's constant
the constant relating the change in energy for a system to the frequency of the electromagnetic radiation absorbed or emitted
quantization
the concept that energy can occur only in discrete units called quanta
photon
a quantum of electromagnetic radiation
dual nature of light
the statement that light exhibits both wave and particulate properties
diffraction
the scattering of light from a regular array of points or lines, producing constructive and destructive interference
diffraction pattern
bright spots and dark areas on a photographic plate
continuous spectrum
a spectrum that exhibits all the wavelengths of visible light
line spectrum
a spectrum showing only certain discrete wavelengths
quantum model
the electron in a hydrogen atom moves around the nucleus only in certain allowed orbits
ground state
the lowest possible energy state of an atom or molecule
standing wave
a stationary wave as on a string of a musical instrument; in the wave mechanical model, the electron in the hydrogen atom is considered to be a standing wave
wave function
a function of the coordinates of an electron's position in three-dimensional space that describes the properties of the electron
orbital
a specific wave function for an electron in an atom. The square of this function gives the probability distribution for the electron
quantum mechanical model
the modern description, primarily mathematical, of the behaviour of electrons in atoms
Heisenberg uncertainty principle
a principle stating that there is a fundamental limitation to how precisely both the position and momentum of a particle can be known at a given time
probability distribution
the square of the wave function indicating the probability of finding an electron at a particular point in space
quantum numbers
numbers which describe various properties of the orbital
principal quantum number
(n) the quantum number relating to the size and energy of an orbital; it can have any positive integer value
angular momentum quantum number
(l) distinguishes orbitals of given n having different shapes; can have any integer value from zero to n-1
magnetic quantum number
m, the quantum number relating to the orientation of an orbital in space relative to the other orbitals with the same l quantum number. It can have integral values between l and - l , including zero. (7.6)
subshell
a set of orbitals with a given azimuthal quantum number (l). (7.6)
nodal surface
node
node
an area of an orbital having zero electron probability
degenerate orbitals
a group of orbitals with the same energy
electron spin quantum number
a quantum number representing one of the two possible values for the electron spin, either +1/2 or -1/2
Pauli exclusion principle
in a given atom, no two electrons can have the same set of four quantum numbers
polyelectronic atoms
an atom with more than one electron
Aufbau principle
electrons enter orbitals of lowest energy first
Hund's rule
when electrons occupy orbitals of equal energy, one electron enters each orbital until all orbitals contain one electron with their spins parallel
valence electrons
the electrons in the outermost principal quantum level of an atom
core electrons
an inner electron in an atim
transition metals
several series of elements in which inner orbitals (d or f) are being filled
E = mc2
Einstein's equation proposing that energy has mass