Atomic Model Vocabulary
Isotopes
Atoms of the same element that have different numbers of neutrons
law of definite proportions
States that a chemical compound will always have the same amount of each element by weight, no matter what the amount is, or source.
Law of Multiple Proportions
States that whenever the same two elements form more than one compound, the different masses of one element that combine with the same mass of the other element are in the ratio of a small whole number.
atomic mass unit (amu)
a mass equal to one twelfth the mass of an atom of carbon-12
cathode ray
a stream of electrons leaving the negative cathode in a discharge tube containing a gas at low pressure, or electrons emitted by a heated filament in certain electron tubes.
atomic theory
a theory that states that all matter is composed of tiny particles called atoms.
Alpha particles
positively charged particles consisting of two protons and two neutrons tightly bound together
Law of Conservation of Mass
states that in a chemical reaction mass is neither created nor destroyed
atomic mass
the amount of matter contained in an atom of an element
mass number
the total number of protons and neutrons in an atom