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Level 158

Electron Configurations & Radioactivity

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Quantum mechanics
invented by a group of people. Branch of modern physics that deals with really small stuff
Planck's atomic theory
precursor to quantum mechanics; for a given frequency of radiation (or light), all possible energies are multiples of a certain unit of energy, called a quantum.
Electron orbitals
defined by the probability function; quantum theory; Heisenberg principle
Energy shells
a collection of orbitals with roughly similar sizes; shape; subshell
S subshell
spherical orbital
P subshell
dumbbell-shaped orbital
oddly shaped orbital
Bohr Model
A simple model of the atom contains a positively charged nucleus orbited by negatively charged electrons in specific orbital shells or energy levels.
Heisenberg principle
electrons are located in orbitals, not orbits; one cannot know an electron's position and momentum at the same time
De Broglie's hypothesis
matter (including electrons) can be thought of as having properties of both a particle and a wave
Aufbau principle
a subshell is completely filled before electrons are placed in the next higher subshell; exceptions: Cr, Cu
Noble gases/Inert gases
elements with stable octets
valence electrons
an electron in the highest occupied energy level of an atom;available to be lost, gained, or shared in the formation of chemical compounds
Alpha decay
an alpha particle is emitted; the atomic number decreases by 2 and the mass number decreases by 4.
Beta decay
a neutron is converted to a proton; a beta particle (an electron) is emitted; the atomic number increases by 1, but the mass number stays the same
Positron emission
a proton is converted to a neutron; a positron is emitted; the atomic number decreases by 1 and the mass number stays the same
Gamma decay
gamma rays are emitted; when emitted, the nuclei become stable
half life
amount of time required for half the original decay