Ch. 3 Sect. 1
the smallest particles of elements
atoms
a very small region located at the center of an atom made up of protons and neutrons
nucleus
a general term for a specific isotope of an element
nuclide
a particle of electromagnetic radiation having zero mass and carrying a quantum of energy
photon
the bending of a wave as it passes by the edge of an object or through a small opening
diffraction
states that mass is neither created nor destroyed during ordinary chemical reactions or physical changes
law of conservation of mass
a positively charged subatomic particle
proton
the weighted average of the atomic masses of the naturally occurring isotopes of an element
average atomic mass
the lowest energy state of an atom
ground state
a three-dimensional region around the nucleus that indicates the probable location of an electron
orbital
the fact that a chemical compound contains the same elements in exactly the same proportions by mass regardless of the size of the sample or source of the compound
law of definite proportions
a neutral subatomic particle
neutron
the amount of a substance that contains as many particles as there are atoms in exactly 12 g of carbon-12
mole
a state in which an atom has a higher potential energy than it has in its ground state
excited state
specify the properties of atomic orbitals and the properties of electrons in orbitals
quantum numbers
if two or more different compounds are composed of the same two elements, then the ratio of the masses of the second element combined with a certain mass of the first element is always a ratio of small whole numbers
law of multiple proportions
the region occupied by electrons
electron cloud
the number of particles in one mole of a pure substance = 6.022 141 79 x 1023
Avogadro's number
when the electron falls to a lower energy level and a photon is emitted
emission
describes mathematically the wave properties of electrons and other very small particles
quantum theory
the distance from the center of the nucleus to the outer portion of the electron cloud
atomic radius
short-range proton-neutron, proton-proton, and neutron-neutron forces that hold nuclear particles together
nuclear forces
the mass of one mole of a pure substance
molar mass
when energy must be added to an atom in order to move an electron from a lower energy level to a higher energy level
absorption
states that it is impossible to determine simultaneously both the position and velocity of an electron or any other particle
Heisenberg uncertainty principle