The smallest particle of an element
Atom
Positively charged mass located in the center of an atom
Nucleus
A positively charged subatomic particle found in the nucleus
Proton
A neutral subatomic particle found in nucleus
Neutron
A negatively charged subatomic particle found in space outside the nucleus of an atom
Electron
A unique number for each element that equals the # of protons
Atomic number
The sum of the number of protons and neutrons in the nucleus of atom
Mass number
Atoms of a given element that have different numbers of neutrons and different mass numbers
Isotopes
A visual model of the most likely locations for the electrons in an atom
Electron cloud
A region of space around the nucleus where an electron is likely to be found
Orbital
The possible energies that and electrons in an atom can have
Energy levels
An arrangement of elements in columns based on a set of properties that repeat from row to row
Periodic table
The pattern of repeating properties displayed by elements in the periodic table
Periodic law
A column of elements in a period table
Group
A row in a periodic table of elements
Period
One twelfth the mass of a carbon-12 atom
AMU
Elements that are good conductors of heat and electric current
Metals
Elements that form a bridge between elements on the left and right sides of the periodic table
Transition metals
Elements with properties that fall between those of metals and non metals
Metalloids
Elements that are poor conductors of heat and electric current
Nonmetals
An electron that is in the highest occupied energy level of an atom
Valence electron
The elements in Group 7A of the periodic table
Halogens
The elements in Group 8A of the period table
Noble gases