atoms of the same element with different numbers of neutrons


electrons in an atom will occupy the lowest energy orbitals

aufbau principle

includes x-rays, ultra violet rays, and infared radiation

Electro magnetic spectrum

applies to different compounds formed from the same 2 elements

law of multiple proportions

region of space where electrons fly


orbitals of the same n and l quantum numbers are each occupied by an electron

hund's rule

positively charged particles produced by nuclear disintegration

alpha particle

if an electron requires additional energy

excited state

exact amount of orbitals occupied in an element

Electron configuration

any sample of a compound always has te same composition

law of definite proportion

present in all atomic nuclei: neutral charge


center of atom


state of lowest possible energy

ground state

number of particles in a mol

avogadros constant

no more than 2 electron occupy a single orbital

Pauli exclusion principle

emission spectrum


positvely charged particle


all matter is made of indivisble particles called atoms

atomic theory

SI unit for amount of a substance


negitive charged particle


mass of an atom

atomic mass

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