Atomic Vocabulary List
atom (see definition) : the smallest particle of an element that has the properties of the element and can exist either alone or in combination
atomic number (see definition) : a number that is characteristic of a chemical element and represents the number of protons in the nucleus
atomic mass (see definition) : the mass of any kind of atom usually expressed in atomic mass units
electron (see definition) : an elementary particle that has a negative charge of electricity and travels around the nucleus of an atom
element (see definition) : any of more than 100 fundamental substances that consist of atoms of only one kind and that cannot be separated by ordinary chemical means into simpler substances
energy level (see definition) : one of the stable states of constant energy that may be assumed by a physical system -- used especially of the states of electrons in atoms
ground state (see definition) : the energy level of a physical system (as an atom) having the least energy of all its possible states
ion (see definition) : an atom or group of atoms that carries a positive or negative electric charge as a result of having lost or gained one or more electrons
isotope (see definition) : any of the forms of an element that differ in the number of neutrons in an atom
molecule (see definition) : the smallest particle of a substance having all the characteristics of the substance and is composed of one or more atoms
nucleus (see definition) : the central part of an atom that includes nearly all of the atomic mass and consists of protons and usually neutrons
neutron (see definition) : a particle that has a mass nearly equal to that of the proton but no electrical charge and that is present in all atomic nuclei except those of hydrogen
periodic table (see definition) : an arrangement of chemical elements in order of atomic number that groups elements with common characteristics in the same area of the table
proton (see definition) : an atomic particle that occurs in the nucleus of every atom and carries a positive charge equal in size to the negative charge of an electron
quark (see definition) : any one of several types of very small particles that make up matter
