Vocabulary and People Flashcard

the smallest particle of an element that retains it identity in a chemical reaction (you can have one atom of an element)
Subatomic particle
small parts within the atom
negatively charged subatomic particle located outside of the nucleus
positively charged subatomic particle located inside the nucleus
the tiny central core of an atom; composed of protons and neutrons
Atomic number
number of protons in the nucleus of a given element; also the number of electrons in a neutral element
Mass number
total number of protons and neutrons in an atom
ex: P+N=mass #-P; N=mass#-P; P=mass#-N
atoms of the same element that have the same number of protons but different numbers of neutrons
Atomic mass number (amu)
defined as one twelfth of the mass of a carbon-12 atom
Atomic mass
weighted average mass of all of the naturally occurring isotopes of a given element
Radioactive isotope
an element with an unstable nucleus; has either: 1. too many neutrons or 2. too many protons
Alpha Decay
when a radioactive nucleus releases an alpha particle
Beta Decay
when a radioactive nucleus releases an electron
Gamma Decay
when a radioactive nucleus releases a gamma ray
Energy Level (E-Level)
the fixed energies an electron can have
Atomic orbital
region of space in which there is a high probability of finding an electron
Principal Energy LEvel
numbered 1,2,3, etc.; for every PEN there is at least one sublevel
mini levels located inside the principal energy level: represented by; “s”, “p”, “d”, and “f”
Electron Configuration
the ways in which electrons are arranged in various orbitals around the nuclei of atoms
Aufbau Principal
electrons occupy the orbitals of lowest energy first
Pauli Exclusion Principle
maximum number of electrons in an orbital is 2 and they must be paired with opposite spins
Hund’s Rule
state that all orbitals in a PEN must be full with electrons of the same spin before being paired up

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