| A | B |
|---|
| Allotrope | One or more forms of an elementary substance |
| AnION | negatively charged atom; an atom that gains an electron |
| Atom | basic unit of structure for all matter; can't be broken down any further by a chemical means |
| Atomic Mass | average mass of all naturally occurring isotopes for an element |
| Atomoic Mass unit (a.m.u) | 1/12th the mass of a Carbon-12 atom; the mass of one proton or one neutron |
| Atomic number | number of protons in an atom of a given element |
| Bohr model | atomic model constructed by Neils Bohr that proposes all electrons can be found in orbitals or paths; electrons must gain or lose energy to jump from one orbital to another |
| CatION | postitively charged atom; an atom that loses an electron |
| compound | two or more atoms of DIFFERNT ELEMENTS chemically combined; always the same ratio |
| electron | virtually massless (tiny) negatively charged particle found outside the nucleus |
| Electron Configuration | arrangement of electrons in an atom or molecule |
| Element | particles that all have the same number of protons in the nucleus |
| Excited state | when an atom absorbs energy and one of more of its electrons "jump" to an orbital further from the nucleus |
| Ground State | when all electrons within an atom fill the lowest energy orbitals; when the electrons are where they would "normally" be |
| Ion | charged atom; an atom that gains or loses an electron |
| Isotope | atom of an element with the same number of protons(atomoic #) but a different number of neutrons |
| Kernel electrons | any electrons found inside the valence shell; the innermost electrons |
| Lewis Dot Diagram | representation of an atom or molecule using only the element symbol and the valence electron arrangement |
| Mass Number | the mass of a given istope of an element; the sum of the masses of protons and neutrons |
| Neutron | subatomic particle with a mass of AMU (atomic mass unit), zero charge found within the nucleus; NEUTRAL |
| Nucleons | any (subatomic) partical found in the nucleus of an atom; a PROTON or a NEUTRON |
| Nucleus | the DENSE, POSITIVE, core of an atom |
| Orbital | a region where electrons of an atom can be found |
| Proton | Subatomic particle with a mass of 1 AMU (atomic mass unit), and a charge of +1 found WITHIN THE NUCLEUS |
| Quantum Theory | used to describe the dual nature of matter; electrons behave like particles and energy |
| Valence electron(s) | the outermost electrons in an atom; there can NEVER be more than 8 valence electrons (OCTET RULE) |
| Wave-mechanical model | states that electrons dont travel in fixed orbits, but that we can use mathematic principals to predict where electrons are most likely to be found |
