Nucleus - The positively charged center of an atom that contains protons and neutrons.
Proton - A positively charged particle located in an atom’s nucleus.
Electron - Negatively charged particles that move around the nucleus of an atom.
Neutron - A particle that has no electric charge and is located in an atom’s nucleus.
Valence Electron - negatively charged particle, located in the outermost shell of an atom, that can be transferred to or shared with another atom.
Electron Cloud - Region where electrons most probably are found surrounding the nucleus of an atom.
Isotope - An atom of one element that has a different number of neutrons than another atom of the same element.
Ion - An atom or group of atoms that has a positive or negative electric charge.
average atomic mass - The average mass of the mixture of an element's isotopes.
atomic number - The number of protons in the nucleus of an atom.
metal - Elements usually having these common properties: shiny, good conductors of heat and electricity, ductile, malleable, are solids at room temperature.
nonmetal - Elements that usually are gases or brittle solids at room temperature; most do not conduct heat or electricity well and other properties opposite to those of a metal
noble gas - any of the elements in Group 18 of the periodic table; unreactive
halogens - Highly active elements in periodic table Group 17; they have seven electrons in their outer shells and readily combine with Group 1 elements.
reactivity- a measure of how readily a substance undergoes a chemical reaction
metalloids - elements that have properties of both metals and nonmetals.
alkali metals - any of the elements in Group 1 of the period table; highly reactive
alkaline metal - any of the elements in Group 2 of the period table; shiny, silvery-white, somewhat reactive metals at standard temperature and pressure
alkaline earth metal - any of the elements in Group 3 of the period table
transition metals - any of the set of metallic elements occupying the central block in the periodic table
inert - a chemical substance is one that is not generally reactive.
periods - A horizontal row in the periodic table of the elements. Elements in a period have varying properties.
groups - Each of the 18 vertical column in the periodic table of the elements. Elements in a group have similar properties.
families - elements that have the same number of valence electrons. Most element families are a single column of the periodic table
metallic elements - the elements on the left side of the periodic table; they include the alkali metals, alkaline earth metals, transition metals and rare earth metals
ductile - ability of metals to be pulled into wires
malleable - Ability of metals to be hammered or rolled into thin sheets.
nonmetallic elements - elements on the right of the periodic table. Non-metals can be gases, liquids or solids. These include the halogens and noble gasses
cation - a positively charged ion,
anion - a negatively charged ion,
subatomic particle - a particle or particles contained in an atom, as electrons, protons, or neutrons